This blog entry expresses some of my less-orthodox opinions on the nature of human evolution, how we got to this point and where we are going as a species. It builds on the arguments set forth in earlier blog entries, Social evolution and biological evolution – another dialog with Marios Kyriazis, and Social ethics of longevity.
Conventional view of evolution
What I learned in grade school and later in high school is that human evolution is driven by “survival of the fittest” and comes about through random variation and natural selection. Later in college I learned that random variation is due to mutations in genes. Further I learned that human evolution happened when we emerged from other primate species, around 2.3 million years ago(ref). And I learned that acquired traits are not inherited. Today, I know these things I learned are either downright wrong to far too narrow. Human evolution is brought about by far more than chance variation and natural selection. It takes place in a far broader context than just the genes. It is happening right now, and it is a far more comprehensive and complex process than originally envisaged. Acquired traits can lead to epigenetic changes and be inherited. Evolution itself has been evolving. A lot.
Getting clear on evolution is important because so many biological processes are routinely explained as having come about as a result of evolution and because many factors affecting lifespans are explainable in terms of evolutionary principles.
For example, calorie restriction, the best-known intervention for extending the lifespans of animals in multiple species, is thought to convey evolutionary advantage because members of these species do not always have abundant sources if food available. Likewise, there is another well-known evolutionary mechanism to protect against starvation in the face of scarcity of food, and that is the body stores energy from excess food consumption in the form if fat. So, given abundant sources of foods that readily convert to fat, that storage mechanism kicks in. Simultaneously there is a change in the epigenome and, when this happens sufficiently frequently like now, there appears to be an evolutionary propensity towards obesity.
There are a great many other matters in biology explainable by applying evolutionary principles, such as the abundant presence of phytochemicals in plants that fight deleterious bacteria or convey insect or draught resistance. It is no surprise that aound 100 if the entries in this blog contain references to evolution.
This discussion is intended to be neutral as to whether the reader views human evolution as a physical process in an objective scientifically-observed universe, e.g., as part of evolutionary biology, or views it is as a process brought about by a basic organizing principle that is beyond science itself, theistic evolution brought about by a higher power such as the God of our religions.
A contemporary view of evolution
I like to think of evolution in very broad terms, for otherwise it is not terribly relevant. Human evolution for me is the changes in what we are as human beings, both physical and behavioral, that result from interaction with our environment. Genetic evolution, what our genes are, is part of this but the change in our genes today is very slow and relatively unimportant. Epigenetic evolution, heritable changes in factors that affect gene expression, is much faster. And it accounts for most changes we observe recently: good ones like increasing longevity and being taller, and bad ones like the propensity towards obesity and diabetes. Diet, lifestyle, work and family habits, exercise, pollution and environmental chemicals contribute towards these changes. Also, there is social evolution which profoundly affects our physical evolution. And there is environmental and ecological evolution which does the same. And there is scientific evolution, evolution in how we explain things and the science-based interventions we apply to shape our health and longevity. I examine some of these facets in turn.
Human evolution is real and highly active right now.
Two indications of this are to be found in human longevity and height. In most Western countries, longevity has been increasing for centuries. See the August 2009 blog post Average US life expectancy up 73 days in one year. That increase appears to be continuing. For 2007, according to the preliminary 2007 statistical report on deaths, the average life expectancy (at birth) in the US was up 73 days in 2007 from 2006, up to 77.9 years. According to the 2010 version of the same report, the same figure for 2010 was 78.7 years. So lifespan in the US, the combined number for men and woman, increased by approximately 10 months between 2007 and 2010. See also We are evolving to live longer – video blog.
With regard to height of humans, this seems to evolve remarkably in response to socio-economic conditions as discussed below. These changes for both longevity and height are not explainable by changes in genes. To move forward we need to get beyond the leather-bound textbook idea that evolution is a trial-and-error process based on gene mutations and takes tens of thousands of years to happen.
Most evolution is mediated by epigenetics, changes in the epigenome, but the evolutionary biology community appears to be very slow at acknowledging that fact.
I wondered why I so clearly have seen epigenetics to be the mediator of most human evolution and, at the same time, literature searches on “evolution” or “human evolution” only rarely and secondarily come up with references to epigenetics. This is despite the fact that many heritable changes have been proven to be epigenetic in origin and even the very definition of epigenetics is “In biology, and specifically genetics, epigenetics is the study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence(ref).” Searching on Google or in Pubmed.com, There seem to be lots of professional articles on historical human evolution, ones on evolution among animal species and few on arcane aspects of human genetic evolution – but almost none raising the topic of epigenetics. Have I been kidding myself when I wrote two blog entries a couple of years ago asserting that epigenetic evolution is the key source of human evolutionary action?
I think the problem lies in large measure with the classical preoccupation of evolution-theorists with genes and the proteins they generate. Actually, a great deal of what makes us different than monkeys, rats or snakes lies not in the genes we and those animals have; they are mostly the same. The difference lies in gene expression, in the epigenetics of non-coding RNAs, in the dark-matter “junk” DNA. This point is made in a May 2010 article Feature: Epigenetics key to human evolution published in Life Scientist. “Epigenetics and RNA, not just genes and proteins, hold the key to understanding human evolution, including the inevitability of the evolution of consciousness, says Professor John Mattick. — Humans possess the most complex Rnome – the RNA equivalent of a genome – of any animal, allowing us to at least lay technical claim to being the most highly evolved species on Earth. Prune down the enormous assemblage of non-coding RNAs (ncRNAs) that are thought to coordinate the activity of our 20,000-odd protein-coding genes, and you might end up with something like a nematode worm, one of the simplest multicellular animals. — “The basic toolkit for multicellular development, such as the Hox body-patterning genes and the Wnt cell-polarity genesare all there in worms,” says Professor John Mattick, of the Institute for Molecular Bioscience at the University of Queensland, and a pioneer in the still-new frontier of Rnomics. — Mattick says the genetic programming of complex organisms has been largely misunderstood for the past 50 years because of the assumption that proteins transact most genetic information. He says that even after more than half a billion years of evolutionary divergence, most genes are still recognizably common to all animal species. All animals share a basic complement of about 20,000 protein-coding genes. In humans, protein-coding genes account for only 1.2 per cent of genomic DNA. — “It is now clear that the majority of the mammalian genome is transcribed into non-protein coding RNA, and that there are tens, if not hundreds of thousands, of long and short RNAs in mammals that show specific expression patterns and sub-cellular locations,” says Mattick. “Our studies indicate that these RNAs form a massive, hidden network of regulation that regulates epigenetic processes, and directs the precise patterns of gene expression during growth and development.” — Thus, the differences between species and individuals emerge from the relative complexity of their RNA-encoded regulatory architectures. Human tissues teem with non-protein-coding RNAs. — “It is now obvious that the differences between us and other animals are not just embedded in the combinatorics of a similar complement of transcription factors,” says Mattick. “They stem from a massive expansion in humans of the genome’s RNA regulatory architecture.”
I have published a number of blog posts on topics of epigenetics recently, including a post on how non-coding RNAs relate to stem cell senescence and appear to hold the key to reversing such senescence(ref).
Human evolution affects the environment and the environment including socio-economic conditions can affect human evolution.
Pollution of oceans, declining fish supplies, deaths of species and increase in atmospheric carbon dioxide are among the well know results of our human and social evolution on our environment. Similarly, shifts in environment can remarkably rapidly affect our biological evolution. From the 1998 Scientific American article Why are we getting taller as a species? “–, conditions of poor nutrition are well correlated to smaller stature. For example, the heights of all classes of people, from factory workers to the rich, increased as food quality, production and distribution became more reliable, although class differences still remain. Even more dramatic, the heights of vagrant London boys declined from 1780 to1800 and then rose three inches in just 30 years–an increase that paralleled improving conditions for the poor. Even today, height is used in some countries as an indicator of socioeconomic division, and differences can reveal discrimination within social, ethnic, economic, occupational and geographic groups.”
In fact, human height seems to vary remarkably with socio-economic conditions in a way that cannot be explained by genes. From a 2005 publication A short history of height: “Canadians are now taller than Americans, who have suddenly plateaued — but all trail the towering Dutch. So what’s their secret? — Richard Steckel has a reality check for parents who see their teenagers sprouting skyward before their very eyes. It’s really happening. Young Canadians today enjoy such stunning nutritional advantage over their predecessors that it is now possible for most to reach their full genetic potential, their optimum height. — Height, it seems, is about more than what’s in our genes. — An economic historian at Ohio State University, Steckel has spent years scouring the boneyards and archives of the western hemisphere searching for clues about the height and health of past populations. He has shown, for example, that in the early 1800s the Cheyenne of the U.S. Plains were among the tallest people in the world, taller on average than Americans and Europeans. At an average of five foot ten for men, the Cheyenne were also taller than their native neighbours to the north, the Assiniboine of Manitoba. Similar genes and cultures. But, Steckel notes, the Cheyenne enjoyed milder winters, enabling them to hunt the high-protein buffalo more easily year round. — Equally intriguing are Steckel’s conclusions about height across the millennia. Northern Europeans in the 11th century were substantially taller — almost three inches taller on average — than their descendants on the eve of the industrial revolution around 1750. That might seem bizarre to anyone accustomed to thinking about human height as something that has increased steadily with the so-called march of civilization. But height varies with how healthy and how well off a given society is as a whole, says John Komlos, a prominent height historian at the University of Munich. “We’ve yet to recognize,” says Komlos, “how sensitive the human body is to socio-economic and environmental circumstances.” — In the late 1700s, for example, American-born colonialists made good use of their sparsely populated, protein-rich environment to become taller than their European contemporaries: average height was five foot eight for American men, judging from military and prison records. That was nearly two inches taller than the average British soldier. Just decades later, however, a strange stunting started to occur that researchers don’t fully understand. American incomes rose from the early to mid-1800s, but that didn’t equate to better living conditions. As Americans became richer — as a group anyway — they also shrank. By the early 1900s, Americans were again among the world’s tallest people. But now measurers are starting to detect another mysterious levelling off. At an average of five foot ten, American-born men from the 1970s are not much taller than their great-grandfathers. So much for the modern diet. — Canada, however, is still shooting upward. At just over five foot eleven, the average Canadian-born male from the 1970s stands nearly an inch taller than his American counterpart. And while it’s nice to be taller than our well-fed neighbours, we still trail the Netherlands, whose citizens are now considered the tallest in the world. Starting in the 1840s, the Dutch began growing from generation to generation, to the point where just over six feet is average for men in their 20s and 30s.” — According to Steckel, it’s the relative equality within Dutch and other European societies that are helping them grow. “If you take a dollar from the richest and give it to the poor,” Steckel says, “heights will increase.” Nations with universal health coverage, protein-rich diets and relatively low income inequality — like the Netherlands and Canada — continue to get taller.”
Physically we as human beings do not evolve as individuals but as synergistic systems of the human microbiome. A single member of the human species is a complex system of our own cells and cells of guest bacteria including some 360 times the number of genes in the human genome. If we are to evolve successfully, we have to co-evolve with some 10,000 additional species of bacteria in us
By far, most of the some 100 trillion cells in my body are not my own and consist of bacteria that function more or less synergistically with my own body cells, e.g., the cells that contain my own genes. According to a 13 June 2012 news release,Human Microbiome Project finds vast individuality in healthy human bacterial populations: “ – In the culmination of a multi-year effort directed by NIH, the Human Microbiome Project (HMP) has announced first genomic compilation of the generalized biome of microbes in the human body that complement the human genome. In a sprawling series of coordinated scientific reports published on June 14, 2012, in Nature and several journals in the Public Library of Science (PLoS), some 200 members of the HMP Consortium from nearly 80 multidisciplinary research institutions report on five years of research. — “Like 15th century explorers describing the outline of a new continent, HMP researchers employed a new technological strategy to comprehensively define, for the first time, the normal microbial makeup of the human body,” said NIH Director Francis S. Collins, M.D., Ph.D. “HMP created a remarkable reference database by using genome sequencing techniques to directly detect microbes in healthy volunteers. This lays the foundation for accelerating infectious disease research previously impossible without this community resource.” — The human body contains trillions of microorganisms—outnumbering human cells by 10 to one. Because of their small size, however, microorganisms make up only about one to three percent of the body’s mass, but play a vital role in human health. — HMP researchers reported that this plethora of microbes contribute more genes responsible for human survival than humans themselves. Where the human genome carries some 22,000 protein-coding genes that carry out metabolic activities, researchers estimate that the microbiome contributes some 8 million unique protein-coding genes or 360-times more bacterial genes than human genes.” — HMP researchers now calculate that more than 10,000 species occupy the human ecosystem. Moreover, researchers calculate that they have found between 81 and 99 percent of all the genuses of microorganisms in healthy adults. — Each body site can be inhabited by organisms as different as those in the Amazon Rainforest and the Sahara Desert. Further, these sites on different individuals are populated with different assemblages of bacteria, or with some of the same bacteria, but in markedly different proportions.”
A human life crucially depends on the synergy between our cells and those of the vast microbiome and when that synergy is disturbed even a small amount, say in the balance of benign vs. pathological microbes, disease and death can soon ensue. We – all my body cells and those companion cells – evolve together Many of these bacteria exist in the gut; see the blog entry Gut microbiota, probiotics, prebiotics and synbiotics – keys to health and longevity. “Humans don’t have all the enzymes we need to digest our own diet,” said Lita Proctor, Ph.D., HMP program manager. ” Microbes in the gut breakdown much of the proteins, lipids and carbohydrates in our diet into nutrients that we can then absorb. Moreover, the microbes produce beneficial compounds, like vitamins and anti-inflammatories (compounds that suppress inflammation in the gut) that our genome cannot produce(ref).”
So, when I take a probiotic capsule or eat some bacteria-rich yogurt I am profoundly affection who the we-of-me are and am affecting my evolutionary path. If I take a strong antibiotic that kills a lot of those gut bacteria, I am also affecting “our” evolutionary history.
Social evolution is enabled by biological evolution and in turn can drive biological evolution. Social evolution and biological evolution are in complex feedback relationships.
By social evolution I would mean the evolution of all key aspects of the environment and behavior of people in a society: how people live, work and communicate, their social, government, economic production and family systems, their institutions of all kinds, the technologies they have and how they have adapted to use of those technologies, what they eat and drink, their belief systems, their expectations and how they think. As apes became bipeds, developed hands and bigger brains and walked on their feet, there were strong evolutionary advantages to them becoming co-operative in families, supporting each other in tribal social structures and developing language to enable them to do so. Animals that are less-evolved physically have also evolved social structures but those structures tend to be far less sophisticated. As society evolves to becoming more and more complex according to its own rules, it takes steps that profoundly affect our biological evolution. For example, after experiencing plagues of infectious diseases due to impure water, society can decide it wants pollution-free water and as a result we are healthier, our epigenome changes and we evolve to live longer. The same can be said for cleaner air and childhood inoculations, the big public health developments of the previous two centuries. Sometimes social developed social evolution produces multiple effects. As the automobile replaced horses for transportation the amount of fecal material in the streets declined and with them incidences of infectious diseases also declined. However, air pollution increased and with cigarette smoking, the incidences of lung cancer have shot up. Antibiotics have saved billions of lives but when massively fed to animals as now have led several pathogen bacteria to evolve anti-biotic resistant strains.
As mentioned, an evolutionary impact in most developing countries resulting from social evolution has been an epigenetically-mediated centuries-old trend to longer lives. Our genes are the same but we have accommodated to living healthier longer lives. Fast-food chains thrive, people consume excessive amounts of saturated and trans fats, epigenomes change and there is an inhereted trend towards obesity and diabetes, another trend in evolution. We build decent cities in which air is clean and people do a lot of walking, and the result is an epigenetically-mediated healthier population. The same is true for public education campaigns against cigarette smoking where they are carried out. These biological trends in turn contribute to social trends towards enjoyment of affluence, marrying later in life, having fewer children and declining populations. Such social-biological evolution exists in Europe, Japan and the US, and is beginning to become manifest in affluent parts of India and China. So social evolution feeds back into our biological evolution and the other way around. And the process is extremely complex confounding cause and effect at every stage.
All sciences have always been in a process of evolution.
I comment that the evolution of human evolution does not stand alone but is a component of evolution of the sciences known to govern the universe. Approximately 13.7 billion years ago, at the initial instant after the big bang, matter, energy, space and time did not exist. None of the sciences we know of today existed. Ordinary matter did not exist so there were no laws of physics at work. Atoms and molecules did not exist so no laws of chemistry were at work, and obviously since there were no living organisms, no laws of biology were in operation. Each of these sciences emerged in a very crude form at a given time and then evolved rapidly at first and, later, slower. I believe all are continuing to evolve now. I am talking about the sciences themselves, the rules of nature and how things work, not about our understanding of them.
For the first 10–32of a second after the big-bang beginning, none of the current sciences existed. It was too hot for even the most basic current laws of physics to be operable. No operable laws of physics, chemistry, biology, sociology, or astronomy existed. Nor anything that could predict what such laws would eventually look like.
After the first 10–32of a second after the big-bang, a few of the concepts of very high-energy physics appear to be applicable, the universe being a quark-gluon mix. Neither ordinary physics or other sciences existed. Many laws of physics of ordinary cool matter did not fully emerge for another billion years when the universe had cooled.
The initial laws of chemistry could only emerge after the elements were created within stars and spun out in space leading later to the creation of molecules, starting about a billion years ago. No laws of biology existed then. Laws of organic chemistry came much later.
The initial laws of biology could come into operation only after the origination of life, thought to be about 2 billion years ago on earth. At any stage of the evolution of life it was impossible to predict what the future would bring. The same, I believe, holds now.
Evolution and my motivation
The fact that social evolution can impact on biological evolution impels me to do the work of generating this blog, I believe increasing awareness as to the possibility of significantly longer lives as well as practical lifestyle interventions to increase health now can and ultimately will assist our evolving to live longer and more productively in a situation of greater democracy and economic equality. And I believe with longer, healthier and productive lives will ultimately come the wisdom and practical application of that wisdom necessary for societal survival and economic prosperity.
I am suggesting a positive model for societal evolution. There is also a negative one that is the opposite.
We need to move as rapidly as possible in the opposite direction of that prevalent in Yemen, Somalia and other countries in Africa and the Middle East and some of our most distressed inner cities. In those areas birth rates are very high, most of the population is under 22, lives are short and not worth much, education levels are very low, family structure is threatened, crime and lawlessness and armed gang warfare are the main ways of resolving issues, religious and tribal fanaticism and preoccupation with an enemy population is the norm, social infrastructure no longer functions, the ecology is less and less supportive of food and life, and starvation and hopelessness is the only outlook.
In the US our population’s background and the prevailing ethics are very mixed. For some of us the rate of social evolution and outlook for health and longevity is very positive. For others of us, there is real danger of slipping into the declining pattern described in the previous paragraph. That is our real enemy. Too much of the debate on these issues has been formulated in terms of polarized right-left politics which has resulted in deadlock. I am suggesting casting the issue of our future in terms of our health and longevity. See my blog post Social ethics of longevity.