Life › The age of mammals › Primates
Monkeys & other anthropoids
by c. 45 million years ago· Organism or group· Human ancestors & us
Strong evidenceGood evidence; dates or details still being refined.
Anthropoids, the primate branch of monkeys, apes and humans, appear by about 45 million years ago.
See it on the Life map →What happened
Anthropoids are mostly active by day, with larger brains than other primates and eye sockets closed off at the back by bone. Small early anthropoids such as Eosimias lived in China about 45 million years ago, and Egypt's Fayum fossil beds, about 37–30 million years old, hold many more. Monkeys reached South America from Africa about 36 million years ago, probably by rafting on floating vegetation across a then-narrower Atlantic.
Why it matters
Anthropoids carried primates into daytime life with sharper vision and bigger brains; one branch, the Old World catarrhines, later produced apes and humans.
The evidence (fossils, genes, rocks)
Teeth and jaws from China, Myanmar and Egypt's Fayum; early South American monkeys such as Perupithecus from Peru, about 36 million years old; and DNA family trees of living primates.
Still debated
Whether anthropoids first arose in Asia or Africa, and exactly how monkeys crossed the Atlantic to South America, remain open questions.
Connections (2)
▸Primates led to Monkeys & other anthropoidsWell established
The connection
Early primates split into two main lines: one leading to lemurs and lorises, the other (haplorhines) to tarsiers and anthropoids. Anthropoids, the monkey branch, became larger, active by day and bigger-brained, with fused lower jaws and eye sockets closed off at the back.
When and how
Asia and Africa, about 50–40 million years ago; Eosimias from China, about 45 million years old, and Fayum fossils in Egypt, about 37–30 million years old.
The evidence
Shared skull features in early fossils, and DNA family trees placing tarsiers as the closest living relatives of anthropoids.
Debates and open questions
The order of branching among early haplorhines is unsettled, and Asian and African fossils point to different birthplaces for anthropoids.
▸Monkeys & other anthropoids branched into ApesWell established
The connection
Old World anthropoids, the catarrhines, split roughly 30–25 million years ago into two branches: Old World monkeys, such as baboons and macaques, and apes. Apes lost the tail and evolved flexible shoulders for hanging below branches. Apes did not descend from living monkeys; both share an earlier catarrhine ancestor, something like Egypt's Aegyptopithecus.
When and how
Africa, about 30–25 million years ago; fossils from Tanzania's Rukwa Rift, described in 2013, include the earliest known ape and Old World monkey.
The evidence
The 2013 Tanzanian fossils, about 25 million years old, match the split time predicted by DNA from living monkeys and apes.
Debates and open questions
Why apes declined while Old World monkeys flourished after about 10 million years ago is debated; diet and breeding speed are leading ideas.