Where did the last common ancestors of all great apes, including humans, live? Until now, East Africa was considered the most likely center of development, but clear fossil evidence was lacking. Now researchers in northern Egypt have discovered the lower jaw of a new hominoid, called Masripithecus, which lived around 17 to 18 million years ago. According to analyses, it is more closely related to today’s great apes than any species of that time known from East Africa. The discovery sheds new light on the geographical origins of great apes.
The earliest great apes, the so-called stem hominoids, emerged more than 25 million years ago in Afro-Arabia and spread to Eurasia around 14 to 16 million years ago, i.e. in the Miocene era, which began around 23 million years ago. But when and where the last common ancestors of all living great apes, including humans, lived is still unclear. “The fossil finds from the early Miocene that document the evolution of hominoids were for a long time limited primarily to sites in East Africa,” reports a team led by Shorouq Al-Ashqar from Mansoura University in Egypt. But paleontologists searched there for the crucial link in vain.
Ancient ape in Egypt
Now Al-Ashqar and his team have found a fossil lower jaw in northern Egypt that dates back to the period in question, 17 to 18 million years ago, and clearly belonged to an early great ape. Fossils of monkeys, but not of great apes, had previously been found in this region. The researchers named the newly discovered species Masripithecus moghraensis. Masri is the Arabic word for Egypt, the Greek word píthēkos means great ape and moghraensis refers to the site in Wadi Moghra in northern Egypt.
The research team’s analyzes show that Masripithecus was significantly different from East African species of the same time. By combining anatomical comparisons, DNA analyzes of modern-day great apes and information on geological age, Al-Ashqar and his colleagues also concluded that the newly discovered North African species is more closely related to today’s great apes than any early Miocene species known from East Africa. The find not only expands the known geographic range of early great apes, but also places Egypt and the entire Middle East region at the center of a crucial evolutionary transition that led to hominids. “If we look closely at the family tree of early great apes, it becomes clear that something is missing – and North Africa holds this missing piece of the puzzle,” says Al-Ashqar’s colleague Hesham Sallam.
Spread from the Middle East to Eurasia
Anatomical studies of the jaw show that it was exceptionally robust, with highly structured chewing surfaces and large canine teeth. “This suggests that Masripithecus was designed for versatility,” explains Al-Ashqar. “The chewing anatomy provides evidence for a flexible, primarily fruit-based diet, with the ability to utilize harder foods such as nuts or seeds when necessary. This flexibility may have helped Masripithecus thrive during a time when climatic changes led to more distinct seasons in North Africa and Arabia.”
According to the researchers, plate tectonics at the time could have encouraged the spread of great apes from Afro-Arabia. The African and Arabian plates were moving north toward the Eurasian plate at this time. Fluctuating sea levels repeatedly created land bridges between the continents. Early great apes such as Masripithecus could have diversified in the Middle East and from there spread to Europe and Asia. “The probability of this scenario does not depend on Masripithecus – but it is very consistent with it,” says co-author Erik Seiffert from the University of Southern California in Los Angeles.
“The Masripithecus findings confirm that paleontologists may have been looking in the wrong place for the ancestors of today’s great apes,” write David Alba and Júlia Arias-Martorell of the University of Barcelona, who were not involved in the study, in an accompanying commentary. “This finding should be greeted with humility but also renewed optimism, as the fossils needed to complete the puzzle of Miocene ape evolution may be out there somewhere, waiting to be discovered.”
Source: Shorouq Al-Ashqar (Mansoura University, Egypt) et al., Science, doi: 10.1126/science.adz4102