Why Do Environmental Scientists Study Human Evolution?

I am an Environmental Science major working on my BS. In one of my classes we were asked to write and essay on the reasons why people who want to understand human impacts on the environment should study human evolution. In preparation, we read Masters of the Planet by Ian Tattersall, which I highly recommend.

Here is my essay. It was sort of done in a rush and I was constrained to some limits because it’s a school assignment (length, taste of the prof, etc) but I thought I’d share it. I don’t know my grade on it yet though. Those who are really sick of reading undergraduate essays written in a desperate frantic sweat the night before will probably want to skip it.

Human Evolution and Cultural Flexibility

The climate in Africa that gave rise to modern humans is dramatically different than the climate in Chicago today, yet humans have lived and thrived in both environments. The environmental conditions that influenced the evolution of humans are different from the conditions in places that humans live now. Seeing the differences between modern life and the lives of humanity’s ancestors sheds light on the aspects of humanity that make us destructive to the environment and also the things that lead to our desire to repair damage and strive to do less harm in the future. In fact, examinations of humanity’s evolution and early history can help show the incredibly capacity humans have for adapting to change and creating change both in the environment and within themselves.

Ian Tattersall’s book “Masters of the Planet” describes human evolution from the earliest stages of the hominid line through modern humanity.Tattersall examines the evolution of humans through the lense of fossil discovery and scientific inquiry. In this way he acknowledges the gaps in understanding of human evolution. Tattersall also communicates the current scientific understanding of human evolution while also recognizing many ways in which this knowledge is incomplete and imperfect. The scientific study of human evolution can itself teach us a fair amount about the changes in humanity’s understanding of itself over time.

During the dawn of recorded human history humans lived very different lives than most do today. The hunter-gatherer lifestyles of early hominid species and most of the history of Homo sapiens doesn’t look much like the culture of an American today. While a few small groups in the world still live primitive lives off the land, most people live in industrial societies. Across the globe humans communicate using electronic technology, create things through industry, and participate in enormous and complex economic systems. Incredibly, this is all done using essentially the same brain that humans have had for thousands of years. Tattersall shows that human brains evolved and changed quite a bit over time, but Homo sapiens is cognitively the same now as it was thousands of years ago.

Even within the industrialized world, human cultures vary substantially from each other. While all human cultures use language, these languages include physical sign languages, languages that use vocal tone to indicate meaning, and those that include clicks of the tongue. Language also changes quickly, with new words becoming common at faster speeds with the use of modern communication technology. Yet the versatile human brain quickly adapts to these changes, learning new words and even new languages rapidly. Other cultural phenomena are enormously varied too, such as family structure, religious beliefs, and food preferences. While there is little biological difference between a child born in the United States and one born in Papua New Guinea, their cultural experiences lead them to live extremely in extremely different ways, building different skills, and seeing the world differently. Human cultural differences may be one of the most clear indications of how plastic and flexible the human brain is.

It is not just the complexity of human culture and technology that sets the species apart from its ancestors, but also the enormous variety of tools and objects that humans create. Many of the ancestors of modern humans used stone tools, one of the most interesting things that Tattersall explains is how long these species used essentially the same hand axes. The precursors to modern humans varied little in the tools they made and how they used them. Not until Homo sapiens did rapid innovation seem to take place. Now the species has a huge range of tools at hand, from thrown spears to tablet computers. The same kind of brain that first learned to control and use fire is also the one that sent humans to walk on the moon.

One consequence of the intellect of Homo sapiens has been the dramatically increased impact the species has made on the planet when compared to its ancestors. Tattersall writes “After a long evolutionary history we have arrived at a point at which our accidental cognitive prowess is allowing us unwittingly to change the very surface of the Earth on which we live” (229). The hunter-gatherer lifestyles of humanity’s ancestors simply did not have the same destructive impact on Earth as modern humans and current cultures do. Understanding the ways in which earlier humans lived may be particularly important for understanding the aspects of humanity that make us destructive to the environment and also the things that lead to our desire to repair damage and strive to do less harm in the future.

Tattersall argues that the changes humans have made to the planet have been entirely unintended. He writes “the only ironclad rule of human experience has been the Law of Unintended Consequences. Our brains are extraordinary mechanisms… but we are still only good at anticipating – or at least paying attention to – highly immediate consequences. We are noticeably bad at assessing risk, especially long-term risk” (227). Humans have not shown a strong history of deciding to make positive changes as a species, but instead often seem to do that which is easiest at the time, without looking ahead at future consequences. The results are as varied as human culture, including the extinction of many species, dramatic changes to the climate, and alterations of landscapes all over the world.

While this may be true of our past behavior, humans have dramatically changed our behavior before. For example, cultures have become substantially less violent, especially since the development of nuclear weapons in the last century. This indicates that in the face of potentially catastrophic consequences humans can, in fact, change in the ways that are necessary to avoid incredible harm. Tattersall also argues that human “brains are the ultimate general-purpose organs, not adapted ‘for’ anything” (228). Perhaps in this flexibility is the key to the future of both humanity and its relationship with Earth.

Since the human brain is so flexible and human intellect so vast, it may be that the threat of environmental degradation, particularly in the form of climate change, may be the key to changing human culture once again. Compared to the enormous changes that humanity has undergone in the past, it seems that a change to a less damaging future isn’t impossible for humans. A change from an environmentally damaging impact to one that instead includes humanity protecting natural systems seems to be a less extreme change in culture than the changes humanity has undergone in the past.

There is reason to think that this change may already be beginning. Humans now have the capacity to communicate globally about the damage being done to the environment, and clearly many people care deeply about making changes to the way humans use resources and impact the planet. Environmental movements, especially against climate change, are growing worldwide. Scientific knowledge, like the information shared in Tattersall’s book, is growing and spreading rapidly. For the first time humanity really has the cultural, as well as mental, capacity to examine itself and see the changes that need to be made. Human brains that evolved to be flexible now have the information to see the risks and harm humans have created and human culture has the ability to spread that knowledge faster than ever.

A major barrier to this change may be the speed that is necessary. Human impacts on the planet have usually occurred over long periods of time and without conscious decisions being made. In order for the human species to change enough to move from a destructive path to a sustainable one the whole population would need to make changes rapidly. An ecological revolution would need to be undertaken with the same speed and intensity as the digital revolution, and it would need to be worldwide to be truly effective. These barriers may be insurmountable; only time will show if that is the case.

If humans do not change their relationship with the planet it is entirely possible that one outcome could be the extinction of the species. One important lesson to be learned from Tattersall’s view of the history of hominid is that human species can, and do, die out. While Homo sapiens have certainly become the most populous species of hominids, that does not mean that they are immune to extinction. If humans make the planet unlivable for themselves it could lead to the species joining its evolutionary ancestors as fossils.

The most important lesson environmentalists can learn from a stronger understanding of human evolution and humanity’s past is that humans can change. Homo sapiens, more than any other species on Earth, has the capacity to change its own culture and its own future. The human brain may not have been very good at recognizing consequences in the past, but no species has ever before had the human ability to change itself. Humanity’s cultural flexibility lead us from hunting and gathering to agriculture and then to the industrial and digital revolutions. This flexibility may also be the key to a future sustainable revolution through cultural evolution rather than the biological evolution of the species.