Will Human Evolution Be Shaped By Climate Change?

Will Human Evolution Be Shaped By Climate Change?

The Arctic is a stunning 20°C warmer than average for this time of year. This is really bad news for layers of sea ice that regulate Earth’s climate, and land-based ice sheets that keep sea levels where they should be. As we stare down a US presidency where the transition leader for the Environmental Protection Agency is a climate denier, it’s easy to wonder whether it’s too late to prevent climate change from destroying our civilisation.

Illustration: Jim Cooke/Gizmodo

But we humans have already proven our ability to survive in an amazing variety of conditions. How might we evolve in the future to face the new climate reality? We asked professors of human origins, human evolution and the philosophy of biology, and speculative fiction author Margaret Atwood, to weigh on on our species’ future.

Michael Ruse

Director of History and Philosophy of Science, Florida State University

At the sensible level, presumably we are going to get more tropical diseases in temperate lands so those with natural immunities to things like malaria will be in good shape — does this mean that sickle cell anemia [which protects against malaria] will become the norm?

The daft idea is something like Kurt Vonnegut’s Galapagos, where we all evolve into seals — then we could all live in the water which will be covering most of the land!

My suspicion is that in the end the super rich will live in mansions in North Dakota or some such place and the rest of us will drown.

John Hawks Vilas-Borghesi

Distinguished Professor in the Department of Anthropology, University of Wisconsin — Madison, human evolution expert and co-author of a study which found that seven per cent of human genes have evolved in the recent past (5000 years), largely in response to environmental change

I’ll be honest — the degree of climate change we are talking about in the next couple of centuries, which is on the order of several degrees Celsius, is by and large going to make the temperate regions of the world more similar in temperature to tropical Africa, where all our ancestors originated. We’re effectively terraforming the world to be more like our origins. The effects on humans are much more social and economic than evolutionary.

To the extent we see evolution, it will be changes in plant and animal species. Some will change the timing of their lives, some will invade new areas where they couldn’t adapt before, and many will become extinct — especially those today locked into small “reserves” that will undergo local climate shifts faster than they can adapt. And of course we will exert our own selection and genetic engineering upon our crops and domesticated animals to suit the changing climate.

Chris Stringer

Research leader in Human Origins at the Natural History Museum, London

The pace of change is likely to be too fast and dramatic for us to evolve physically to meet the challenges of a much warmer world. Any changes would have to come from cultural or social accommodation to the new situations — if that proves possible.

Stephen Stearns

Professor of Ecology and Evolutionary Biology, Yale University

We won’t be adapting biologically, not for centuries. All the short term reactions will be cultural.

[This could mean] mass migration from the lowlands — Micronesia, Bangladesh, Florida, Gulf Coast, Nile Delta, Tigris/Euphrates delta, possible disruption of agriculture by drought and floods leading to crop failures and starvation … Possible major shifts in long-established patterns of climate, e.g. much colder winters in Europe.

CRISPR-CAS should allow editing of human DNA. Problem is, we don’t understand the consequences because we do not know how all the parts of organisms are internally connected. [There’s] potential for very unpleasant surprises.

Margaret Atwood

Speculative fiction author

Human beings will either evolve in response to climate change if given enough time — that is, if the change is slow enough — or they will try to tech-fix, in which case they will not be pushed to evolve. Will they learn to breathe more methane and CO2, or construct oxygenation machines? If, however, the change is too fast and severe, they will most likely just go extinct. Alas.

Joseph L Graves

Associate dean for Research & Professor of Biological Sciences Joint School of Nanoscience & Nanoengineering, North Carolina A&T State University

Adaptation can only occur if there is a relationship between specific environmental conditions and differential reproductive success. Another aspect of whether adaptation can occur is the rate of change in an environmental parameter and the range of genetic variation within the species. This would be particularly true for animal species where evolution would have to rely on the standing genetic variation in the species.

If we were to assume that global temperature continued to increase at very slow rate, it might be possible for human populations to undergo natural selection for resistance to these increasing temperatures. It would be difficult to speculate what such adaptations might look like, but one area of concern would be resistance to novel pathogens resulting from the expansion of transmission zones of vector insects (tropics to former temperate zones).

We have already observed the increase in transmission of Zika virus as a result of expansion of vector insects. If malaria transmission were to expand as a result of increasing temperatures we might see renewed selection in favour of antimalarial adaptations in populations inhabiting formerly temperature zones. With regard to unpredictable weather (hurricanes, tornadoes) it is highly unlikely that humans could evolve mechanisms to adjust to an increasing frequency of these events. Survival in such cases in highly unpredictable and would in no way be related to an individual’s genotype.

However, it will be extremely difficult to make predictions beyond the most basic ones I mentioned above. So much of this will be conditioned upon human technological capacity to deal with changing climatic conditions. For example, should a clean renewable energy source (e.g. nuclear fusion) be developed that would allow a much greater potential to adjust to new climatic conditions due to readily available and cheap energy.

On the other hand, should we not develop such a resource, the rate of climatic change is likely to accelerate. It might accelerate at rates making biological adaptation no longer possible to the rapidly changing conditions, in which case the collapse of modern civilisation and possibly the extinction of our species is the most likely result.