Primates: our ‘ancestors’ were already living around 70 million years ago

According to the results of the statistical analysis, the first primates very probably had different forms of social organisation. Most of them probably lived in pairs. Only 10-20% of individuals were solitary. Keystone / Hugh Kinsella Cunningham

The first primates were probably already living around 70 million years ago, contrary to popular belief. A study by the University of Zurich suggests as much. The social structures of our "ancestors" were more similar to our own than previously thought.

“It has often been claimed that the first primates were solitary beings and that other forms of social organisation only developed later”, write the researchers in their study published in the specialist journal “Pnas”. Previous studies have tried to establish how and when pair life appeared in the evolution of primates.

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However, the most recent research has shown that, in reality, many primate species that are active at night – and therefore difficult to study – live in couples. Lemurs and strepsirrhinids are among them, the University of Zurich reported on Wednesday.

Database of over 500 populations

To find out what this meant for the ancestors of all primates, researchers from the Zurich alma mater and the University of Strasbourg gathered information on the composition of wild groups of primates. They have built up a database covering almost 500 populations of more than 200 species.

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Using a comprehensive statistical analysis, the scientists calculated the probability of different forms of social organisation based on variables such as body size, diet and living space.

To reconstruct the form of social organisation of ancient primates, the researchers used fossils. These show that they were smaller than many of today’s species and that they lived in trees.

10-20% solitary, as in humans

According to the results of the statistical analysis, the first primates very probably had different forms of social organisation. Most of them probably lived in pairs. Only 10-20% of individuals were solitary.

“We too often – but by no means always – live in couples. At the same time, we are members of large families, larger groups and societies,” compares study director Adrian Jäggi.

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