Review of Kurzweil’s “How to Create a Mind”

Kurzweil has a solid reputation as an inventor of technically-advanced products that have very practical use. He is also a famed a futurists, and a shrewd businessman who has without a doubt learned how to capitalize, popularize, and monetize his own and other’s ideas and visions: some brilliant, some not so much according to skeptics.

As the New Yorker recognized, Kurzweil’s critics have not always been kind; PZ Myers, a renowned biologist once indicated that he is a genius… and one of the greatest hucksters of our time. The author of “Gödel, Escher, Bach,” Pulitzer Prize winner Doug Hofstadter said reading one of Kurzweil’s books was like mixing together good food with dog excrement: ultimately you can’t tell the good from the bad.

The astute reader will be aware of commercialization and hyperbole but not be dissuaded by it. Rather, I suggest you read to enjoy the broad strokes and general principles behind the ideas presented and use them as a catalyst to explore the various aspects he put together in an attempt to explain one of many possible approaches to achieving human-like artificial intelligence- that particular goal only one of several possible paths to self-directed thinking, perhaps consciousness, and sentience in a machine. See our Introduction to Artificial Intelligence for a brief overview of the various AI perspectives.

May Kurzweil’s collection of ideas inspire your imagination.


Kurzweil subscribes to the theory that Artificial Intelligence machines will soon be equaling the power of human thought-with all of its complexities and richness- and perhaps even outstripping it.

The rather broadly held theory is lent credence by some two major turning points;- In 1997, Gary Kasparov was beaten at Chess by Deep Blue of IBM, and in 2011, Watson an Artificial Intelligence machine also of IBM beat Brad Rutter and Ken Jennings in the Jeopardy Chess matches.  He uses these two events to support the argument that the neuro-networks responsible for higher level/ hierarchical thinking (known as the Neocortex) actually have simple principles that can be well replicated, and that some of the more advanced AI machines such Siri- iPhone’s voice recognition software- and the aforementioned Watson already have the pattern recognition scheme used in their installed “brain”.

Kurzweil explains that this pattern recognition scheme is naturally hierarchical, meaning that lower-level patterns that pick minute inputs from the surroundings combine, triggering higher-level patterns picking more abstract categories that must be taught. Also, information moves upwards and downwards, causing feedback between higher and lower order patterns in a theory called the Pattern Recognition Theory of the Mind (PRTM), similar to the design of our best AI machines, and with a little tweaking- Kurzweil continues- will make it possible to design computers that match human thought, with such features as Identity, consciousness, and free will by 2029, eventually outstripping even human capabilities since they don’t have such biological incapacities as will be explained later. This advance, though, will allow us to use technology to update our neurochemistry in a merger Kurzweil calls the “singularity”.

It should be pointed out to the reader of this review, that the Singularity has morphed into several definitions. Originally conceived it simply meant the point at which machine intelligence surpasses human intelligence. Machines have concepts and thought beyond our comprehension, developing even faster and smarter machines further separating us from the new masterminds of the universe. See more on our treatment of that in the Human Extinction: Risks to Humanity section.


The ability to reason, analyze and prioritize enables mammals to think abstractly, as well as be predictive so we can processes, manipulate and store information from which we can adapt to or change a surrounding based on what we have learned about it. This intelligence comes from the Neocortex, which was added to previously existing sections of the brain by evolution.


The Neocortex gives mammals like humans the ability to think hierarchically and to understand singular parts of larger groups, groups that also belong to much bigger groups, and so on, helping us survive and thrive in two ways; It gives us a detailed and precise likeness of our surroundings and allows us to understand and adjust to the surroundings as our thoughts climb the levels of hierarchies, becoming more abstract and complex. The lack of the Neocortex- some scientists believe- contributed to the extinction of dinosaurs. Mammal Neocortex differ in size and development and account for 80% of the weight of human brain.

Neuroscientist Henry Markram of Switzerland deduced that the Neocortex can be reduced to a single thought process- hierarchical thinking- because of its uniform structure, as found out in a study where he scanned mammalian Neocortexes in search of neural assemblies. He indicated that the Neocortex appeared to be constructed of Lego-like collections of several dozen neurons in layers, connected to similarly structured super-assemblies connected to yet a higher layer of neuronal collections, and so on until the highest level represented the entire brain.  He is now a Director at the Blue Brain project, intent on recreating the complexities of the human brain, beginning with a trial on rats.


 The Pattern Recognition Theory of Mind (PRTM)

The author, borrowing from others before him, says that each layer of neural assemblies stands for a pattern recognizer that finds hierarchically organized information in the surroundings whether auditory, linguistic or any other information. Neural assemblies are pre-organized and innate, but are taught at each level of the neural assembly, incorporated with exact information. Human higher level thinking uses some 30 million recognizers and writes all information into different levels of neural assemblies in our brains.  For example, on a human face the mouth and nose are recorded at a different neural assembly from the entire face such that even if some facial parts are absent, a face can still be recognized especially if enough parts of it are available to trigger a recognizer and send the information to the next upward level.


Before a pattern recognizer at one hierarchical level triggers another one higher, they prime it before sending signals back to recognizers at the next-lowest level, to prime and prepare their senses for firing. In this instance, if a person’s eye is detected, the recognizers for the face will be primed before signaling to those representing other parts of the face to detect given features. The author considers this predictive.

Pattern recognizers communicate with positive or negative signals to encourage or hinder firing depending on the possibility of a given pattern to exist and whether they come from lower or higher conceptual levels.

Every new or change in a sensory scenario is detected by the brain and is saved given a new pattern recognizer. Some, like different expressions of a relative are saved multiple times while redundant ones, like a face not seen for ages are eventually replaced to save storage space. This replacement causes memory to fade away slowly to the extent that a face seen before is no longer remembered. Pattern recognizers have a redundancy factor of about 100 to 1 depending on importance (like between relatives and first sighting).

This example is exclusive of the great abstraction levels that we reach with alarming regularity and means. According to the author we might not, for example, remember a reason for laughing yet remember that we did laugh. We must also note that these signals are sent at very high speeds and pattern recognizers fire across many given faculties at any given time.

The reach and presence of the Pattern Recognition Scheme

As can be seen below, different mental capabilities from the Neocortex are found in multiple brain parts, and other parts of the Neocortex are available to perform tasks that are assigned to any other parts should it be found that the said parts are damaged or missing from birth (brain cells in various locations can be “taught”, or rather learn to be multifunctional if necessary for survival. This is known as neural plasticity and has even been found in people having congenital defects.


Introducing Speech Recognition to Artificial Intelligence

As Kurzweil shows, advanced artificial intelligence machines and software programs already use the processes described of the Neocortex above.

When the author and other computer scientists first moved into the uncharted territory of artificial intelligence, they sought to solve problems using predefined intelligent solutions and  programmed these problem types and solutions into a computer to be applied to arising problems as they came. Speech to text conversion (1980’s) was first tackled in this way- recording digital patterns which the program would try to match against human voice inputs. But since enunciation and pronunciation differ between people of different nationalities or races, or even with one person as they age, this method quickly became impracticable- too many variations would be needed in the “answer” databank.  Kurzweil then tried another technique known as vector quantization: to summarize or reduce human speech into 1,024 points/ iterations.

He then recreated what goes on in a person’s brain while they spoke and simulated this so that the computer could identify new units of speech, as well as variations in enunciation and pronunciation using a technique very mathematical in nature known as the Hidden Markov Model which could “infer a hierarchy of states with connections and probabilities.”

With this done, he sought to set parameters of unknown data points and their organizational hierarchies, using the biological evolution and cross-bred multiple ‘solution organisms’ (genetic codes of multiple parameters) which even had mutations that were not definite, or properly defined in their parameter values. Multiple cross-breeding tests were conducted, where in the best resultant designs were set aside and used for setting parameters for the Hierarchical Hidden Markov Model (HHMM). This HHMM was trained with speech samples from people of different nationalities and races, and who had unique accents to learn “the likelihood that specific patterns of sound are found in each phoneme, how the phonemes influence one another, and the likely orders of phonemes.” At the end of the day, the HHMM discovered/ learned that there were different rules, which were very different yet delicate, but more importantly were much more useful than the previous hand-coded rules used. In short, as Kurzweil and team combined HHMMs to simulate the cortical organization that accompanies human learning and a genetic algorithm to simulate the biological evolution that gave rise to a particular cortical design. Both of these are self-organizing procedures. This became the cornerstone of subsequent speech recognition works and research, and is being used in other areas of AI like speech simulation and knowledge of natural languages.

The need for both self-organizing and pre-programmed systems

While self-organizing systems are generally more advanced than pre-programmed ones, Kurzweil says artificial intelligence machines are incorporated with both, especially because the pre-programmed systems are much faster when handling familiar information and present a good basis for lower conceptual levels of hierarchy. These two advantages over the otherwise more advanced self-organizing systems enable the self-organizing system to learn much quicker than it would do on its own, and be ready for practical use much faster.  Combining both optimizes an effective AI machine. After the self-organizing system has fully learned, it’s expected that the pre-programmed system will be discontinued.

Watson; The Most Advanced Machine in AI

According to Kurzweil, Watson is an AI machine which uses an ‘expert manager’ called UIMA (Unstructured Information Management Architecture) to choose the correct sub systems for use in different situations and then with “intelligence” combines the outcomes (answers) of these systems. This method allows Watson to contribute to a resolution even though it may not deliver an actual answer to a given problem.  This multi-processing also helps to gauge and build Watson’s confidence in its answers by use of a probability percentage. This example of probability percentages was witnessed at the Jeopardy matches. Kurzweil says the human brain also uses this method when statistical inference is used to resolve multiple hypotheses.

According to the author, Watson was designed around the complexities and richness of the Neocortex, although admittedly it’s still some way from posing as an actual human. For example, it could not ace the famed Turing test because it was never designed to pass it nor engage in intelligent conversation, rather it was designed to compete at Jeopardy and answer brief and not so complex questions. Kurzweil, though, believes with a little tweaking, Watson will perform those tasks considering that many AI advances occurred before the complexities of the Neocortex were well researched.

Simulating the Human Brain

Multiple attempts with varying degrees of success have been made to accurately simulate the human brain, ably assisted by technologies including the scanning technology used to uncover the grid-like patterns of the Neocortex’s connections.  There a number of such technologies including the latest MRI techniques which are noninvasive scanning technologies.

Human Connectome

The National Institutes of Health, through their Human Connectome project have chosen to use this technology and expect to build a complete 3-D map of the human brain complete with all its connections by 2014.

The Blue Brain Project

The Blue Brain Project, on the other hand aims to model and “simulate the human brain, including the entire Neocortex as well as the old-brain regions such as the cerebellum, amygdala, and hippocampus, and by recording the measurements of ion channels, neurotransmitters, and enzymes that generate and regulate every neuron’s electrochemical activity. They will be using a patch-clamp robot, another scanning technology, in a system that is automatic and able to scan neural tissue at one micro-meter of accuracy, avoiding the destruction of delicate membranes. In 2005, participants simulated one neuron, and in 2011 did a neural mesocircuit of 100 neocortical columns.  They target 10,000 neurons and a rat brain by 2014. Their current goal is 2023 for fully-simulated Human Brain.

Educating the simulated brain

According to Kurzweil, the simulated brain cannot achieve human-level thinking unless it has the necessary content and he describes multiple potential methods to fulfill this requirement. The most likely, he surmises, is one that can simplify molecular models by creating functional equivalents at different levels of detail, starting with his personal functional algorithmic method to simulations that are closer to full molecular simulations. His book goes into greater detail, but he guestimates that it could speed the learning process 1000 fold or more.

Technological acceleration

Kurzweil explains that future-human-evolution-and-exponential-technology-growthhis Law of Accelerating returns (LOAR) is doubted by many because they don’t understand the concept of linear vs. exponential progressions where if forty linear steps is equal to 40 years, the same 40 steps on an exponential scale would equal a whopping trillion years. Based on the historical evidence of exponential advancement, he predicts more complex advances are coming, merging biological and technical evolution techniques. He confidently speculates on the possibility of a machine having human consciousness, identity and free will, purporting that any complex physical system will inevitably develop it.  He cites man’s best friend, the canine, as an example of a non-human consciousness.

Consciousness, Free Will and Identity?

He also argues- concerning free will- that there’s a likelihood that we humans actually don’t have it, but just feel that we do, or alternately, like consciousness, perhaps it’s also an emergent property that evolves at high, complex levels. If these are true then it’s likely possible that a machine of human-level thinking would also have the same, or feel (have the perception) that it does. Kurzweil holds that identity is borne of our sense of free-will and experience. He extrapolates that a self-aware machine would naturally possess the same belief.

Beyond Human Intelligence

Kurzweil is also a proponent of the more advanced applications of AI. Synthetically producing a Neocortex and replacing our own biological one would enable the functioning of more than 300 million processors- or more. A billion?  He considers the fact that digital neurons can be made to link up wirelessly- a big advantage over human ones which are linked physically.

He also considered the possibility of adding bug cleaning features to our brains, to remove/ reduce instances such as multiple thinking and inconsistent but colliding ideas in our brains. A module for detailed thinking could be designed to continually do background scans for inconsistencies in all existing ideas or patterns and update their compatibilities with each other. Inconsistent ideas would then be reviewed or eliminated. With this and other such implants, we would alleviate the risk of AI machines ever outstripping us in intelligence.  We could then take advantage of the singularity by incorporating the exponential advances into our own biology. By doing so we could dispel some fears of losing our identity or changing the continuity of our body cells any more than nature replenishes them for us currently.


It’s only fair to say we are in a race with technology which is ever advancing.  His far future vision is the spread of our non-biological intelligence to the four corners of the universe, infusing our deliberate will directly upon its fate.  If we are able to break the speed of light barrier we could have a universal omnipresence within a few centuries. It is our destiny.

Certainly on that last conclusion this reviewer and this site agree.  Science fiction writers and far futurists have been coming to that conclusion for years as well. See our own 2003 essay on the distant future. It is in fact the only logical conclusion to an assumed eternal existence in the known universe (although we disagree with the assumed ubiquitous non-biological entity).

In any case, let us all hope the boundaries of reality continue to expand the unknown at least as fast as our ability to consume and understand it, lest we be caught in the forever loop of The End is Just the Beginning.

Further Reading

Fashionable Genetic Engineering

fashionable-genetic-engineering-and-the-future-of-human-evolutionWhile not immediately obvious, genetic engineering as a fashion tool does have its implications for the future of human evolution.  What happens when a particular characteristic becomes unfashionable? Or more alarmingly, what if certain looks or traits become ubiquitous? Studies have shown that looks and intelligence alike (both genetically determined) are directly related to societal success in terms of position, power, and pay. As the ability to choose these ‘successful’ looks becomes readily available and affordable, will we become a homogeneous Orwellian society not only looking alike, but also thinking alike? Would this be bad? How would it affect human evolution in its broadest sense? What influence would this trend (or the potential counter trend) have on the species?

The momentum of genetic engineering has long since achieved critical mass. With the mapping of the human genome a decade in the past, the race is now on to associate specific sequences of DNA (nucleotides) that make up genes, to traits that manifest in physical form.  Several hundred genetic diseases can be identified via genetic markers and eliminated in future humans (through non-engineering means). Technically, the process of creating recombinant DNA continually improves through experience on plants, animals, and even with human genomes in the context of medical research. A substantial amount of current research funding comes from governmental departments, particularly in the USA, as well as research grants. Institutions are also receiving support from organizations such as the Cancer Research Society. Billions of dollars are being invested in genetic engineering research by the biotechnological industry, and to a lesser extent the pharmaceutical industry who see the potential for huge profits as agreed upon by market analysts and investors.

At present, the highly profitable beauty and health industries have the market cornered: plastic surgery for enhancement is common practice.  Creams to stop wrinkles abound on pharmacists shelves, anti-aging pills, memory pills, pills to make you more potent. Implants for breasts, butts, calves, and cheeks abound. But some companies within the biotechnology field are gearing up to challenge that position. Increasingly we desire to alter ourselves and are willing to spend the money doing it, it is not unheard of for people to save for years to pay for surgery to, for example change the much hated nose. The technology for engineering our offspring is getting closer every day and it won’t be long before we can give our children a head start by deciding which characteristics, features and traits we want for them.

The time is also rapidly approaching when we will be able to use the benefits of genetic engineering to alter ourselves.

The Science

To be able to achieve changes to our current appearance scientist are looking at growing, manipulating and altering adult stem cells. These are the undifferentiated cells that are present in the body and get called upon when a repair or renewal job is needed. The recent advent of 3-D printing and its combination with biological material create unprecedented opportunities to grow, replace, and/or enhance one’s own body with bioidentical cells: zero chance of rejection.  There is also a significant field of study into the use of stem cells and gene therapy within dentistry. Recently (2013) researchers in China were able to generate mice teeth from stem cells as a proof of concept.

The Debate

The first paragraph of this article posed a number of questions:

  • What if certain looks or traits become unfashionable or conversely, ubiquitous?
  • Will we become a homogeneous Orwellian society not only looking alike, but thinking alike?

There are a number of influences to be considered in trying to anticipate the use of genetic engineering for fashion. There are innate forces that drive many people to highly value and exhibit individualism, there are cultural norms and the influence of our parents and the world we see around us from birth, and there is the ever-increasing influence of visual mass media shaping our perceptions and values.


Our sense of ourselves and the need for individuality which we all possess to one degree or another may override the desire to conform to the requirements of the latest fashion.  Certainly the small but important segment of the population who are born and remain rugged individualists their entire lives will resist assimilation. And there will always be non-conformists, those who deliberately kick against the trends, occasionally creating countertrends. And let us not forget the often maligned rebellious youth: young enough to procreate and wild and free enough express their desire for a new world genetically.

Cultural and Parental Influences

future-human-evolution-parental-influence-on-beautyIf we look at the world today, it seems that we find that the old adage ‘beauty is in the eye of the beholder’ to still be true. Across the world definitions of beauty vary extensively according to locally established norms and ideals.  As newborns, the mother’s breast we suckle and whose face becomes recognizable according to some studies as early two days old, the firm hands of our father or other adults that hold and caress us as we look into their eyes. As we grow, the other children and people in our neighborhood, peers in school, and exposure to extended families all help shape our ideals of normal, beautiful, and desirable.

The Power of Visual Mass Media

A major influence on that which we wish to emulate is visual mass media. At the time of the original writing of this article, we mentioned that the public has certain perceptions about the type of person that should be performing what type of role in society, and people may choose to alter themselves accordingly. We used “pretty” young females as a mismatch for news anchor roles. At the time it was true. A lesson we’ve grown to understand is this: public perceptions are extremely malleable. The power of visual media, now coming at us from the time we’re infants and following us everywhere we go thanks to the mobile internet, can and has altered public perception, societal values, and our ideals of beauty, fashion, and desire.  It is possible that the greatest influence on the future of human evolution is already wielded by the owners of movies studios, television networks, and production houses.  It would be a sad commentary on society, though perhaps true nonetheless, if the majority of parents selecting a genetic upgrade for their children were highly influenced by whom the media portray as glamorous and successful.

Will these harbingers of the future human promote sameness and a narrow range of heroes, heroines, and idols, or will they promote a future that values and celebrates diversity in genotype, phenotype, culture, talents, and accomplishment?  Will human nature and individualism triumph over hypersocialization and conformity? Will cultural and parental influences prove stronger than commercial and the special interests of the few?

In the end, we believe that the human race is comprised of enough individuals who value their individuality and who will standup for their own and their children’s rights for genetic freedom and diversity to prevent an unnecessary narrowing of the gene pool and to keep a strong, robust variety essential for happier, healthier lives.  It is up to each of us, according to his or her daily actions, to create a positive future.  The Future of Human Evolution.

What future will you help create?

Liv Tyler’s “Perfect” Face. The Future of Human Evolution?

Courtesy Qupic via Deviant Art

Future Human Speciation

future-human-evolution-speciationSpeciation is the process by which a new species is formed from a single initial species. There are a number of theories that might explain the phenomenon. For the astute visitor to our site, the rapid changes soon to be made possible in the human genome through the application of genetic engineering, combined with the geographical separation afforded by space colonization makes for an easy extrapolation of the process to humans.

George Lucas unwittingly had it right at the cantina in Star Wars. What he missed was the fact that all of the species gathered there at the watering hole were all from a common lineage; humans on earth having spread millennia ago, separated by distance, and subject to both direct germ-line manipulation and the environmental forces of the local planetary (or system) conditions.

Visit our Future Visions section for a look at some theoretical future human species.

Below we look at a few of the theories of how speciation occurs.

Speciation Theories

In order for speciation to occur, the following events must happen:

  1. There is a single species, made up of a set of interbreeding organisms.
  2. A genetic variant must spread through part of the species and the bearers of this variant must mate only with other bearers of the same variant.
  3. The species will have now split into two: from one initial population, two separate interbreeding populations will have evolved. Along the way, further phenetic, behavioral and ecological differences may also evolve.

Speciation comes about when there is recombination and isolation between different groups of genes, so that no longer can genes in one group be recombined with genes in another group. Once this occurs there is selection within each group of genes to interact well with the members of their own gene pool but there is no selection for them to be particularly functional with members of the alternate gene pool.

The crucial event, for the origin of a new species, is reproductive isolation.

Biologists need to understand how a barrier to interbreeding can evolve between the new species and its ancestors. There are three main theories as to how this can happen:

  • Allopatric speciation in which the new species evolves in geographic isolation from its ancestor.
  • Parapatric speciation: the new species evolves in a geographically contiguous pair of populations.
  • Sympatric speciation: the new species evolves within the geographic range of its ancestor.

Allopatric speciation

Allopatric speciation occurs when a new species evolves in geographic isolation from its ancestor. It can happen like this:

One species could split into two if a physical barrier, such as a new river, divided its geographic range. If the barrier is large enough, gene flow between them would cease and the two separate populations would evolve independently. Over time, different alleles would be fixed in them, either because of the hazards of mutation and drift, or because selection favored different characters in the two.

If the two populations are separated long enough for significant divergence to have taken place, then if the barrier is removed and the populations reunited, they might remain distinct from each other. A prezygotic or postzygotic isolation mechanism would prevent them from interbreeding. There would now be two species where there was formerly one.

A single randomly mating species is widely distributed through a geographical region.

Quite suddenly, a natural barrier forms, dividing the species into two separate groups.

Over the succeeding generations, either through selection or random events, the two populations come to differ.

When the barrier is removed, the populations are now so different that there is no reproduction between them: they have become two distinct species.

Peripheral isolation: a form of allopatric speciation.

There is a form of allopatric speciation called peripheral isolation or peripatric speciation.

In peripatric speciation a small population, at the extreme edge of the species’ range, is separated off. The same sequence of divergence and possible meeting of the two populations could then take place as in speciation by subdivision.

It has been argued that peripatric speciation has been much commoner than standard allopatric speciation. There are two reasons for this:

It may be physically more probable that a small population would be isolated at the edge of a species range than that a barrier would divide the whole of a species range.

It is thought to be common for isolated populations at the edge of a species range to be distinct in form, whereas the individuals in the main part of the species range show less variation. For example, the kingfishers on the peripheral islands have diverged more than would be predicted from the degree of variation on New Guinea.

There are two possible explanations for this divergence:

  1. Local adaptation: the conditions on the island may be such that natural selection favors a distinct phenotype there.
  2. Isolation: gene flow from the rest of the species may be reduced on the island, allowing the population there to diverge.

Whatever its explanation, if peripherally isolated populations are likely to diverge from the form of their ancestors, they may well be a common stage on the way to speciation.

Peripheral speciation may produce interesting features

Peripherally isolated populations are likely to be small, perhaps living in relatively extreme conditions and possibly having a non-representative sample of the ancestral species’s genes. Because of this, controversial conjectures have been made about how speciation works via peripherally isolated populations:

The speciating population may evolve rapidly (because the population is small) and by drift as well as selection.

The founder effect: the peripheral population is formed by a small number of founder individuals, who lack some of their ancestor’s genes. This is a controversial idea, because it implies that speciation might be non-adaptive.

Speciation might be accompanied by a genetic revolution: an extensive re-organization of the gene pool, which takes place in the extraordinary genetic and environmental conditions of the peripherally isolated population.

Parapatric speciation

In parapatric speciation, the new species evolve from contiguous populations.

Parapatric speciation occurs as follows:

Suppose that a population initially existed in an area to which it was well adapted, and that it then started to expand into a contiguous area in which the environment favored a different form. If the transition between the two environments was sudden, a stepped cline would evolve at the border.

As selection worked on the population in the new area, different genes would accumulate in it and the two populations would diverge to become adapted to their respective environments. If they diverged almost to be different species, the border would be recognized as a hybrid zone. The two populations would have separated while they were geographically contiguous, along an environmental gradient.

In contrast to the allopatric theory of speciation, the two populations on either side of the hybrid zone have diverged without any period of geographic separation.

Sympatric speciation

Sympatric speciation describes the splitting into two of a species without any separation of the ancestral species’ geographic range. Apart from hybrid speciation, which will be discussed later, it has been a source of recurrent controversy whether sympatric speciation ever happens.

Sympatric speciation could occurs as follows:

Imagine a bird species in which beak size determines the type of food the bird can eat. If the food is seeds, then there will be some distribution of seed sizes in the environment. Suppose also that there are several genotypes influencing beak size in the bird population. The fitnesses of the genotypes will be negatively frequency-dependent because as there are more birds with a certain size of beak they will compete with each other for food and lower one another’s fitness. There will be a stable polymorphism of beak genotypes.

Provided the seed sizes have a flat distribution as in the figure, the different genotypes will not have equal fitness. Birds with extreme beak sizes will experience less competition for food, and have higher fitness. In this circumstance, selection will favor assortative mating (tendency of like to mate with like) for beak size. Birds at the edge of the distribution by mating assortatively would produce more offspring like themselves, and therefore with higher fitness, than if they mated at random. As selection fixes assortative mating, the population will split into two new species: one with long beaks, the other with short.

The general conditions for sympatric speciation are therefore that the genotypes are adapted to different resources and the limited resources generate frequency-dependent selection. Then if the resources are not in the frequencies of the genotypes generated by random mating, sympatric speciation becomes a possibility.

Hybrid speciation

There is one type of sympatric speciation which is uncontroversial and well known to exist: hybrid speciation which regularly occurs in plants.

Interspecies hybrids are usually sterile because the chromosome pairs, which consist of one chromosome from one species and another chromosome from the second species, do not segregate regularly at meiosis.

When a hybrid species evolves, this sterility can be overcome by polyploidy: the chromosome numbers are doubled. Each chromosome pair at meiosis contains two chromosomes from one species, and regular segregation is restored. Polyploidization is encouraged by applying the chemical colchicine in the commercial production of new species. Many popular species of garden flowers such as these tulips (opposite) have been created like this. Hybrid speciation can also occur naturally at a low rate. In this case, a new hybrid species may evolve. Some hybrid species also evolve without polyploidy; the initial sterility of the hybrid is overcome by some other genetic means.

Polyploid hybrids are interfertile among themselves, but reproductively isolated (by the mismatch in chromosome numbers) from the parental species; they are therefore well defined new species.

Two problems likely to arise in the transition from a rare new hybrid genotype to a full hybrid species:

1. Finding a mate.

When a fertile polyploid hybrid first arises, it is one hybrid (or perhaps one of a small number) within two large populations of the parental species. The hybrid can only mate with other hybrids like itself and so natural selection on the hybrid therefore has a kind of positive frequency dependence: when it is rare its fitness is lower because of the difficulty of finding a mate.

This helps explain why hybrid speciation has been much commoner in some groups of plants than others. It is much easier for a new hybrid to cross the difficult transition stage, in which it is rare, if it has alternative reproductive options besides sexual cross-fertilization. It has been shown that hybrid speciation is commoner in groups in which asexual reproduction or self-fertilization are possible.

2. Ecological competition.

Two species with identical ecological needs will usually not be able to coexist; if one of the species can survive on a lower level of resources, it will drive the other extinct. When the hybrid arises, it will be in the same place as the parental species, and it is likely to have ecological needs that overlap with them. It is therefore thought that the hybrid species that have become established are those that happened to be adapted to different ecological niches from the parental species.

Those that were ecologically too similar to the parental species would have been lost. The survival of Iris nelsonii (pictured opposite in its swamp land habitat) may have been helped by the way it lives in habitats in between the other three species.


Reinforcement is the process by which natural selection increases reproductive isolation.

Reinforcement can occur as follows:

When two populations which have been kept apart, come back into contact, the reproductive isolation between them might be complete or incomplete. If it is complete, speciation has occurred. If it is incomplete, hybrids would be produced. If the hybrids had lower fitness than either parental form, selection would act to increase the reproductive isolation because each form would do better not to mate with the other and form the disadvantageous hybrids. Speciation might then be speeded up by favoring genes which caused individuals to avoid mating with hybrids.

Reinforcement is a necessary requirement for both the parapatric and sympatric theories of speciation. It is the process by which a hybrid zone (an area of contact between different forms of a species) develops into a full species barrier.

Secondary reinforcement

Reinforcement is known as secondary reinforcement if the reproductive isolation has partly evolved allopatrically, and is then reinforced when the two populations come into secondary contact. Reinforcement could occur whenever two forms coexist, and the hybrids between them have lower fitness than crosses within each form.

Reinforcement can be simulated by artificial selection experiments. By continually selecting for assortative mating (the tendency of like to mate with like), it has been possible to obtain significant changes in prezygotic isolation mechanisms. However, the theoretical conditions for speciation to take place by reinforcement are difficult and it is controversial whether the process takes place in nature.

Gene flow

There is also the factor of gene flow. Selection might reinforce any isolation between the populations but, until isolation is complete, gene flow will be acting to equalize their gene frequencies. Once the two populations become genetically the same, there can no longer be selection to decrease breeding between them. Selection for reinforcement is likely to be strongest immediately after the two populations meet. If the necessary genetic variation in mating preferences is present, and selection is strong enough, the two species may completely split; but a gradual slide back into a single species is possible.

Allopatric speciation does not need a theory of reinforcement

A theory of speciation can avoid theoretical difficulties if it does not depend on reinforcement. The allopatric theory has this virtue. In the allopatric theory, it could be that reproductive isolation only ever evolves in allopatry (and when it does not the two populations simply collapse back into one when they meet); alternatively, it could be that partial reproductive isolation sometimes evolves allopatrically and is then reinforced on secondary contact. Either possibility fits in with the general theory of allopatric speciation.

The two alternatives – parapatric and sympatric speciation – require the theory of reinforcement: if reinforcement does not operate, neither do they.

Chromosomal evolution

It has been suggested that chromosomal evolution is exceptionally important in speciation. The theory runs like this:

Consider two forms of a chromosome, differing in an inversion. We can call the standard and inverted forms A and A’ . Suppose that A and A’ have identical sets of genes and produce the same phenotype, as in figure A. The two kinds of homozygote (AA and A’A’ ) will have identical fitness. The heterozygote is likely to be selected against, because recombinants between the two forms may have double sets of some genes, and lack others. We have here a precondition for the evolution of assortative mating. AA types should preferentially mate with otherAA types and avoid crossing with A’A’ ; and vice versa. A gene causing its bearer to mate assortatively with respect to chromosomal genotype will be favored. If assortative mating becomes established, speciation will result.

Applying the theory

If the theory is correct, we can predict an association between whether or not the members of a taxonomic group have an inbred population structure, their rate of speciation, and of chromosomal change.

Some species live in small social groups, or otherwise have subdivided populations, and in these the degree of inbreeding will be higher than in a species in which individuals outbreed in a large population. Bush et al. tested whether genera whose members live in small family groups have a higher rate of speciation and chromosomal evolution than panmictic genera.

They collected evidence for 225 vertebrate genera. For each, they counted the number of species in it and its chromosomal diversity. The two are correlated, as would be predicted by almost any theory. They then argued that the taxa with higher speciation rates tended to have subdivided population structures; mammals, especially primates and horses (though not whales), have high rates of speciation and chromosomal evolution; amphibians, reptiles, and fish have lower rates – which perhaps explains the existence of living fossils. Primates (like these chimps pictured opposite) and horses are two taxa that usually live in social groups.

It is therefore possible that taxa with subdivided population structures do have higher speciation rates, and maybe this is due to the way chromosomal evolution can proceed more rapidly in these kinds of species.

Speciation – Summary

The evolution of a new species happens when one population of interbreeding organisms splits into two separately breeding populations.

It has been a matter of controversy whether new species evolve only from sub-populations that are geographically isolated (allopatric) from the ancestral population, or whether they can also evolve from sub-populations that are contiguous with (parapatric), or overlap (sympatric), the ancestral population.

Allopatric speciation may be by subdivision of the species range or by a peripheral isolate – a small population which becomes cut off at the edge of the species range.

Parapatric speciation could happen if a steep cline evolved into a hybrid zone and barriers to interbreeding then evolved.

Sympatric speciation is most likely if selection first establishes a stable polymorphism and then favors assortative mating within each polymorphic type.

Many new plant species have originated by hybridization of two existing species, followed by polyploidy of the hybrids.

Reinforcement is the enhancement of reproductive isolation by natural selection: forms are selected to mate with their own, and not with the other, type. Sympatric speciation requires reinforcement to happen; parapatric speciation usually requires it; allopatric speciation can take place with or without reinforcement.


Projecting Human Evolution: 5 traits we might possess in the future

Internet author Bryan Nelson makes some interesting and entertaining predictions in his article Mother Nature article “Projecting human evolution: 5 traits we might possess in the future” from May 2012. Using current and past trends to predict our next evolutionary traits, his article is certainly stirring some debate.

Bryan suggests that future humans will lack wisdom teeth, become hairless, become resistant to heart diseases and diabetes, be of a similar race and be relatively weak with susceptible immune systems – all traits- he says- that will develop because we no longer use them or will get used to them.



Could this be a future human? Small, hairless, no wisdom teeth.

The Hardy-Weinberg equilibrium, an evolutionary principle says that evolution is possible whenever anyone influence of natural selection, gene flow, genetic drift, mutation or non-random mating is present. Naturally, the conclusion is evolution is an ongoing business. After all, as he clearly points out, we depend heavily on machines to do heavy work, so will become weaker in future and wil become susceptible to pathogens because we don’t need our natural immune systems due to modern medicine.  And from history, he claims, humanity has always shed off traits it doesn’t need.

So according to Mr. Nelson, we will evolve into a completely machine dependent species owing to our increasing dependency on them, lose our wisdom teeth because we no longer have stuff as hard as our ancestors had to bite into, our bodies will eventually get used to the junk food we eat and develop resistances to diseases that these foods cause, and that currently increasing interracial sexual relationships will ultimately make us all of one race.

You can find his original article on the Mother Nature Network.

FUTURE HUMANS: Four Possible Evolutionary Paths

In his article “Future Humans: Four ways we may or may not Evolve” dated November 24, 2009, James Owen honored the 150 year anniversary of Charles Darwin’s “On the Origin of Species” by documenting what a few scientists speculate on some popular ways we humans may, or may not, evolve be as digitized electronic immortal beings or cyborgs bound in muscle.

four ways future humans may evolveHis first documented prediction considers the possibility that human evolution is in fact dead. In this prediction, he argues against Darwin’s ‘survival of the fittest’ concept by suggesting that even the weakest survive long enough to transfer their genes to the next generation, thanks to medical advances. At the time that Darwin came up with this concept- James Owen notes, only a half of Britain’s population grew to the age of 21. Currently, that figure sits pretty at 99%.

Also, increased human mobility means a lot of cross-breeding among humans, indicating that Darwin’s theory of natural selection becomes irrelevant: there is no isolation therefore little chance that the fixation of any significant biological novelties would appear from which to select. We’re all stuck trading about the traits that currently exist in the gene pool.

His second relayed prediction- that evolution in humans will continue- also considers natural selection but Owen takes another view. On the one hand, in an increasingly complex technological world, mates will be selected for their ability to thrive in this new environment and average intelligence will increase as a result. Of course the proponent of this notion fails to take into account the actual inverse relationship between income and quantity of offspring that occurs in the real world.  As another part to the second prediction, on scientist argues that advancement in human biotechnology will ultimately make it possible for humans to select the best genes for themselves and especially their offspring. The end result will be an entire generation of humans with attractive characteristics such as height, masculinity, intelligence, health, and social status. Also, our immune systems will become stronger as pathogens travel ever increasingly to different corners of the earth, helping humans to become universally immune.

Four ways future humans may evolve

Four ways future humans may evolveJames Owens’ documented third prediction is a bit more far reaching; that humans will evolve into electronic immortals. This prediction considers the concept of transhumanism, a form of unnatural selection that is much faster than natural selection. Here, humans will live forever, use uploaded (and faster) minds (using advanced operating systems), download themselves to become robots at will and even travel at the speed of light as a pattern of information. Imagine reducing your food budget right to zero! These ‘humans’ will have brains that are scanned- one atom at a time and uploaded on computers. Even better, ‘copying’ will mean that humans wouldn’t need to take the biological 20 plus years to mature- they could just be mature in seconds, experiencing the years of angst via simulated reality in torrents of electrons.

Four ways future humans may evolveFinally, the author looks at the possibility of colonizing off world as an evolutionary direction.  Here, James Owen wonders what would happen if some humans just went on one way voyages into space and to some new places on the solar system. He considers the possibility that some habitable planets might be discovered, then some humans (perhaps all) would migrate to those planets. They would eventually likely develop features that would make them ever more comfortable there.

See the original National Geographic article here.