Our primate ancestors evolved in the cold—not the tropics

Most people imagine our first prime ancestors swinging through lush tropical forests. But new research shows that they were causing the cold.

As a ecologist who studied chimpanzees and lemurs in the field in Uganda and Madagascar, I am fascinated by the environments that have shaped our Primate ancestors. These new discoveries overthrow decades of hypotheses on the way – and where – our line has started.

The question of our own evolution is of fundamental importance to understand who we are. The same forces that shaped our ancestors also shape us and will shape our future.

The climate has always been a major factor stimulating ecological and evolving change: what species survive, which adapt and which disappear. And as the planet warms up, the lessons of the past are more relevant than ever.

The cold truth

The new scientific study, by Jorge Avaria-Lautureo of the University of Reading and other researchers, maps the geographic origins of our Primate ancestors and the historical climate in these places. The results are surprising: rather than evolving in warm tropical environments as scientists thought before, it seems that the first primates lived in cold and dry regions.

These environmental challenges have probably been crucial to push our ancestors to adapt, evolve and spread to other regions. It took millions of years before the primates colonized the tropics, according to the study. The warmer global temperatures do not seem to have accelerated the spread or the evolution of primates in new species. However, the rapid changes between dry and humid climates have led to an evolutionary change.

One of the first known primates was Teilhardina, a small tree resident weighing only 28 grams – similar to the smallest primat living today, the mouse of Madame Berthae. Being so small, Teilhardina had to have a diet rich in calories of fruit, gums and insects.

The fossils suggest that Teilhardina differs from other mammals of the time because he had nails rather than claws, which helped him grasp the branches and manage food – a key characteristic of primates to date. Teilhardina appeared approximately 56 million years ago (around 10 million years after the extinction of dinosaurs) and species quickly dispersed from their origin in North America through Europe and China.

It is easy to see why scientists supposed that primates have evolved in hot and humid climates. Most primates are living in the tropics today, and most primate fossils have also been put to the ground.

But when scientists behind the new study used data from fossil spores and pollen from the first fossil surroundings of primates to predict the climate, they discovered that the locations were not tropical at the time. Primates are in fact from North America (once again, going against what scientists had once believed, in part that there are no primates in North America today).

Some primates have even colonized the regions of the Arctic. These first primates may have survived seasonal cold temperatures and a significant lack of food by living a bit like species of mouse and dwarf lemurs today: slowing their metabolism and even hibernating.

Difficult and modifiable conditions have probably favored primates that have moved a lot in search of food and better habitat. The species of primates which are with us today come from these very mobile ancestors. Those less capable of moving have not left descendants alive today.

From past to future

The study demonstrates the value of the study of extinct animals and the environment in which they lived. If we want to keep primate species today, we must know how they are threatened and how they will react to these threats. Understanding the evolutionary response to climate change is crucial to keep the primates of the world and other species beyond.

When their habitats are lost, often by deforestation, primates are prevented from moving freely. With smaller populations, limited to smaller and less diversified areas, today’s primates do not have genetic diversity to adapt to changing environments.

But we need more than knowledge and understanding to save species of world primates, we need political action and change in individual behavior, to combat the consumption of bush wicks – the main reason why primates are driven by humans – and the reverse loss of housing and climate change. Otherwise, all primates are at risk of extinction, especially ourselves.

To learn more about the diversity of primates, behavior and threats to their survival, see Monkeys: our family of primates, while the exhibition puts an end to its international tour with a return to the National Scottish Museum in Edinburgh.

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