Are Humans Still Evolving?

Are humans still evolving?

Check out this answer from Consensus:

The evidence strongly supports the notion that humans are still evolving. Both biological and cultural factors contribute to this ongoing process, with significant implications for health, genetic diversity, and adaptation. As our understanding of human evolution continues to grow, it becomes clear that our nature is far from static, and evolution remains a fundamental aspect of our existence.

The question of whether humans are still evolving is a topic of significant interest and debate among scientists. While some argue that modern advancements and cultural evolution have halted biological evolution, others present evidence suggesting that human evolution is ongoing. This article explores various perspectives and findings from recent research to provide a comprehensive understanding of the current state of human evolution.

Evidence of Ongoing Evolution

Recent studies indicate that humans are indeed still evolving. For instance, research utilizing data on lifetime reproductive success, genetic variation, and covariation in traits from long-term studies suggests that human nature is dynamic and continues to evolve1. These studies employ methods to predict evolutionary changes and measure selection and inheritance in contemporary human populations.

Genetic and Environmental Influences

An analysis of the human genome reveals that human evolution has not occurred in the manner biologists initially expected. Early Homo sapiens, who migrated out of Africa around 60,000 years ago, faced numerous environmental challenges that led to novel genetic mutations spreading through populations via natural selection. However, most detectable natural selection has occurred slowly2. This slow pace of natural selection is contrasted by the rapid cultural evolution that has significantly influenced human adaptation.

The Role of Cultural Evolution

Cultural evolution plays a crucial role in human adaptation, often leading to rapid adaptive changes in response to cultural innovations. This has important implications for infectious diseases, genetic diseases, and systemic diseases in current human populations. The increase in human population size and global mobility has also induced a rapid evolutionary shift in genetic variation distribution, diminishing genetic differences between populations and increasing individual heterozygosity, which has beneficial health effects5.

Contemporary Evolutionary Forces

The increasing movement and panmixia of humans, coupled with the unprecedented growth of the global human population, suggest an intensification of natural selection in the near future. This ongoing evolution is driven by various forces, including positive Darwinian selection, genetic drift, and transmission distortion. Despite the complexities and uncertainties, the idea that human evolution will cease is increasingly difficult to sustain4.

Health and Intelligence Implications

Some researchers argue that the high survival rates of children in affluent countries might lead to the accumulation of adverse genetic mutations, potentially affecting health and intelligence in future generations. This hypothesis suggests that while natural selection may not be as stringent as in the past, it still plays a role in shaping human genetic potential3.

 

 

Are humans still evolving?

Richard Edwards has answered Near Certain

An expert from UNSW Sydney in Bioinformatics, Molecular Biology, Evolutionary Biology, Genomics, Genetics

It is certainly true that cultural and technological evolution are occurring at much faster timescales than biological evolution. It is also true that our technological and culture has probably overpowered many of the historical drivers of “natural” human evolution. Nevertheless, evolution never stops. We may have altered the selection pressures that drive the evolution of our species – indeed, in many cases we may be able to control those pressures – but the genetic makeup of our species is still going to change with time in response to disease, mate choice etc.

 

Are humans still evolving?

Benjamin Hunt has answered Near Certain

An expert from Birmingham University in Cardiovascular Disease, Clinical Trials, Clinical Research, Cell Biology, Stroke, Microbiology, Diabetes, Biology, Evolutionary Biology, Molecular Biology, Public Health

Absolutely, along with every living being on the planet!

Our technological and cultural changes, alter the strength and composition of the selection pressures within our environment but selection pressures still exist. A great example of a recent (and binary) change to a selection pressure comes from the eradication of the smallpox virus in nature. If we hadn’t of done this then over a protracted length of time it is conceivable that we would have evolved a defence against the virus (at least to the point where mortality was reduced or eliminated) e.g. evolution would favour genes which protect against smallpox. However, now that Humans will hopefully never encounter smallpox again (it still exists in labs), the hypothetical changes that might have taken place will not.

Most changes to selection pressures aren’t binary like the example above and so the evolutionary change they confer are typically even slower. However, we are still very much evolving. For example, due to our increasingly sedentary lifestyles, evolution might favour higher metabolic rates, decreased appetites, or (although probably undesirable) disorders such as anxiety which might cause you to fidget and pace more. Keep in mind that an evolutionary change isn’t always advantageous in a holistic sense, it only has to serve to increase the ability of the population to reproduce well and reproduce as frequently as possible, so anything that extends life is likely to come under this umbrella.

 

Are humans still evolving?

Chris Robinson has answered Near Certain

An expert from The City University of New York in Palaeoanthropology

This question stems from a fundamental misunderstanding of what evolution is. Evolution is defined as a change in the allele frequency of a population through time. If, for example, the percentage of the O blood type allele among New York city residents was 40% in 1980 and is currently 41%, evolution has happened. There is no doubt evolution is and will always happen in humans since allele frequencies change over time randomly (which can occur by a process known as genetic drift and also via mutation) and through gene flow from other populations. The question seems to be conflating evolution via natural selection (i.e., adaptation) and evolution writ large. If the questioner had asked, are humans adapting or has cultural or technological (especially medical) evolution led to humans being buffered from the environment, that would be a more interesting question. Still, the answer would be, yes, humans are adapting to their environment. Examples of this include the gradual loss of our wisdom tooth potentially due to softer diets (although with the spread of dentistry the disadvantage of having impacted wisdom teeth is not as great) but more clearly adaptations to high altitude observed in many populations (e.g., in the Andes and Himalyas).

 

Are humans still evolving?

Aylwyn Scally has answered Near Certain

An expert from University of Cambridge in Genetics, Evolutionary Biology

As long as human reproduction involves randomness and genetic mutation (and the laws of the Universe pretty much guarantee that this will always be the case at some level), there will continue to be differences from one generation to the next, meaning that the process of evolution can never be truly halted.

However people tend to think about evolution primarily in terms of selection, i.e. the pressure of environmental or other factors that make some traits more advantageous and more likely to increase in frequency. Although it is true that some selection pressures have been eased for some humans – e.g. some childhood or early life diseases in developed countries, this represents a small minority of the factors which affect one’s fitness or chance of producing offspring. Even in developed countries we still suffer from genetic diseases, and there may be many other interactions between our biology and the environment that affect the chances of reproduction or the number of children produced. (Note also that the prolonging of life after childbearing age has minimal evolutionary effect.)

As to whether cultural and technological evolution have ‘overtaken biological evolution’, it is difficult to assess their relative strengths, and they probably vary for different human traits. However for most traits affecting fitness I would say it is almost certainly not yet true that our environment is dominated by culture and technology. This is particularly evident when you consider that the vast majority of humans alive have far less access to medical and other technology than those in the wealthiest countries.

 

Are humans still evolving?

Stanley Ambrose has answered Near Certain

An expert from University of Illinois at Urbana-Champaign in Anthropology, Evolutionary Biology

The simplest definition of genetic evolution is: Change in gene frequencies over time (between generations). This includes mutations that are passed from the individual in which it occurred, to the next generation. At the population level, any change in the proportions of genes or gene variants over time is also considered evolution. The variants may be functionally equivalent, so evolution does not automatically equate with “improvement” in the gene pool. In fact, deleterious genetic mutations also pass between generations.

 

Are humans still evolving?

SARAH BARBER has answered Near Certain

An expert from University of Central Florida in Anthropology, Archaeology

Natural selection operates on all living things, including humans. Numerous examples of changes in human morphology just in the past 10,0000 years have been documented, including changes in jaw size and tooth eruption since the adoption of agriculture. Human technology is also affecting individual and population reproductive success, for instance by allowing people with poor hearing and sight to survive to reproductive age.

 

Are humans still evolving?

Ivor Janković has answered Near Certain

An expert from Institute for Anthropological Reasearch in Palaeoanthropology, Anthropology, Archaeology

Yes. Evolution cannot be stopped because evolution is change. The common misconception is that it is also increase in complexity (which may be true, even the predominant outcome of biological evolution, but not true for all organisms).

The question whether humans are still evolving is very common, as most people confuse evolution (which can be defined as biological change, regardless of the direction of change) with evolutionary mechanisms. Not to go into much details, but there are four main mechanisms of evolutionary change.

1. natural selection, which works on individuals that survive and pass their genes to the next generation – and given their biological characteristics, including physical, genetic, behavioral, physiological and so on – they will have statistically better chances of survival in a given setting. To put it simply, if being a fast gazelle is a favorable trait in an environment in which it increases chances of not being eaten, over time, more fast gazelles are likely to survive and pass their genes to the next generation. It is important to make a distinction between a single gazelle, that may be fast, but unlucky and trips and still gets eaten (this is how natural selection works on individuals) and population of gazelles in which statistically faster individuals will survive and pass their genes in a larger percentage than slower ones (unless the whole population of that gazelle group are clumsy ones, in which case, well bye bye gazelles – but that is highly unlikely).
2. the second major mechanism of evolutionary change is mutation. Mutation is random and simply means change in certain genetic detail (which may or may not prove favorable in a given setting, and the survival of the trait will be determined mostly by the aforementioned mechanism of natural selection).
3. gene flow – another major evolutionary mechanisms, which works through genetic exchange within populations of a species. Simply put, fertile mating, which allows that various genetic – and other traits, are passed within a larger interbreeding community (species). This mechanism is important, as it decreases the chance of a given species to separate and over time evolve into a separate species.
4. genetic drift – this mechanism is the exact opposite to gene flow, as it increases the chance that part of a species (population) over time and through isolation, becomes a separate species which no longer can interbreed successfully (that is have fertile offspring) with the starting population from which it separated. Now all these four mechanisms are always active, and whether a new species will arise depends on many factors, basically through interplay of these mechanisms and external factors (including environment and so on).

Another major thing to explain, is that people usually think evolution results in drastic, observable changes (mostly in phenotype, or physical traits) and results in a new species (often called macroevolution). Yes, that can happen and often does (as is testified in endless forms most beautiful that we see all around us), but does not have to. Evolution, as said, is simply a change, no matter the direction or how great the results may seem to the observer. Your child is not the same as you. That is the result of evolution. Most of evolutionary changes are small and within a population, or species (or, for that matter, on even smaller levels) – this is called microevolution. In addition, the pace of evolutionary change (on any level) can differ – sometimes it is slow and takes a long geological time, sometimes it is rather fast (at least in geological terms) and if we turn to fossil record, it can seem almost instantaneous (yet it is not so).

The pace of evolutionary change also depends on many factors, one of the major ones being the circumstances that affect individuals (and populations and species and so on) in their specific setting and time. To put it simply, if organisms are adapted well for the environment and other organisms with which they interact (whether as food or otherwise), evolutionary mechanisms, and specifically natural selection, will favor the already present characteristics and the result is what we call stabilizing selection (it will look much like bell curve, with most individuals closer to its axis). If the circumstances change, evolutionary mechanisms (and natural selection) will favor change in the direction of characteristics that will increase chances of survival in the new setting. If the change in circumstances (environment etc etc) happens slow (let’s say, over hundreds of thousands or millions of years) then a species (or population, or genus etc) will change slowly (this is most often seen as true Darwinian evolution – gradual change over time). However, if the change in circumstances are rapid (that is over hundreds or thousands of years), then a species (or population, or genus, you got the picture) will change rapidly (or die out, just as rapidly, both happens, in fact over 99% of once living species are now forever gone). This, more rapid evolutionary pace of change is often referred to as Punctuated equilibria (the model most coherently proposed by S.J. Gould and N. Eldredge in 1972) and often seen as an alternative to Darinian gradual model of change – which is not (as anyone can conclude based on what I’ve said above). In truth, both models work, as the pace of change is not constant at all times and at all places and for all species.

So, getting back to the answer about humans. Humans are a part of the animal world, and as biological organisms, we are sucseptible to all above described mechanisms of evolution. Yet, we are weird animals, as we have culture (and had it for a long time in our evolution, but that is another, no less interesting story). Our cultural, technical and technological adaptations and inventions (and some biological, as many anthropologists will argue, language being one of them) allowed us to influence our environment much more that it is possible for other organisms (yet, another story for debate). In this way, humans have changed some evolutionary rules (or rather, they bend them somewhat). What results from all this, is that, given these cultural (technological, technical etc etc) adaptations, and the fact that we are spread all over the globe in such numbers and that all humans generate a globe-wide interbreeding network, it is highly unlikely that a new species of humans will arise in near future. That is, unless some catastrophic event causes a fast and major decline in population size and some smaller groups become isolated and our culture, technology etc cannot overcome these difficulties. Then, we could (as has been known to happen during the last several millions of years of human evolution) see a new species of humans to arise. OK, back from this dreadful scenario, and just for the sake of philosophical argument with tech nerds (no offence given), one could argue that future technical enhancements that may become a part of our biology will create a new species of humans. Well, that is another story.

Coming back to the initial question. The answer (after all being said here) is still yes. Because evolution is change. You cannot stop change.

 

Are humans still evolving?

Eva Hesping has answered Near Certain

An expert from Griffith University in Biology, Chemistry, Biochemistry

The definition of biological evolution is a slowly and gradual shifting of genetic material from generation to generation. So yes, humans are still evolving. Due to sexual selectivity, gene-drifting and natural selectivity, the gene-pool changes the way how evolution works.

 

Are humans still evolving?

György Csaba has answered Near Certain

An expert from Semmelweis University in Developmental Biology

As I wrote in my paper entitled „Thoughts on the cultural evolution of man. Developmental imprinting and transgenerational effect” (Riv Biol 2007, 100, 461-474) the human biological evolution stopped and had been conveyed to the cultural evolution, as a continuation of biological one. My standpoint did not change since this time. During the cultural evolution tools had been developed, which not only able to substitute human properties, but can further develop them and can help man to do such things which could be inaccessible without them (e.g. X-ray, to see which is inside the body, space travels, etc). However, evolution at a molecular level can be imagined at present and in the future (and it will be indeed as a consequence of human activity, as environmental pollution), but the basic structure and functions of man will not be altered.

 

Are humans still evolving?

Ole Andreassen has answered Likely

An expert from University of Oslo in Genetics, Pharmacology

Human evolution is an ongoing process. On a superficial level one may think that biological evolution is being supplanted by cultural and technological evolution. Research has however concluded that the opposite might be true. A study by Stefánsson et al. in 2015 found that the rate of evolution in humans could be faster than previously thought (ref: doi:10.1038/ng.3171)

Any evolution is not an end point but a way of adapting to the environment. As long as the environment changes our bodies and our genes will continue to change. A research by Belsky et al. even suggests that nature selects genes that are more flexible and adaptable to the environment even if it is potentially harmful (ref: 10.1038/mp.2009.44). Since our origin, we have evolved to become lactose tolerant (ref: doi: 10.1098/rstb.2010.0268), adapted to malaria with sickle cell trait (ref: doi: 10.1073/pnas.1505665112) and have evolved to adapt to certain geographic regions. Tibetans and Andeans have adapted to be more efficient living in oxygen deficient areas. As a very recent study points out Indonesian divers have evolved to have bigger spleens to stay underwater (ref:doi:10.1126/science.aat9261).

Not all evolutionary changes have been positive though. A study in Iceland suggested that natural selection might be acting against educational attainment mainly because those with higher education are having children later in life and fewer children (ref: https://doi.org/10.1073/pnas.1612113114).

In the future, evolution will likely continue to be driven by factors such as diet and lifestyle. The fact that we are living longer, have managed to treat many illness, women in industrialized societies are in greater control of child birth also has profound influence in how our genes are being transferred to future generations. Finally, evolution is a very slow process and takes a long time. In the big scheme of things, humans are a very recent creation. Therefore, it might not be easy to detect or visualize how we are changing or have changed.

 

Are humans still evolving?

Gordon Gallup has answered Likely

An expert from University at Albany in Evolutionary Biology

Contrary to what most people have been led to believe, evolution is not about the survival of the fittest.   Evolution is not about competition for scarce resources and it’s not a matter of whether you live or die.  We all die.  

Evolution focuses on reproductive competition and the perpetuation of genes. Genes get transmitted from one generation to the next through reproduction.  Therefore sex is the final common path for all evolutionary change.  In order for anything to evolve it has to confer a reproductive advantage.   

The key to evolution is that although everyone dies, not everyone reproduces and among those who do some have more children than others.  If individuals carrying certain configurations of genes leave more descendants than those carrying other genes, those configurations will become more prevalent.  Therefore as long as some people leave either more or fewer descendants than others, humans will still be evolving. 

For most of human evolutionary history people with bigger brains left more descendants.  That is the only way brains could get bigger.  But human brains are no longer getting bigger.  Because of the widespread availability of effective contraception, nowadays well educated intelligent people are having fewer children.   

On the flip side, however, it could be argued that effective and inexpensive contraception will eventually lead to selection for better parenting. Increasingly the only people who have children will be people who want children, and people who want children will be better parents than those who don’t.