According to recent study, apes' upright height was not caused by their ability to gather fruit in trees, as previously believed by anthropologists, but by their lifestyle in open woods and diet of leaves. The discovery moves the beginning of upright apes and green woods from 7 to 10 million years ago to 21 million years ago.
In order to reach fruit, giant apes must spread their weight on the outer limbs of the tree and then extend their hands towards the fruit. An upright ape makes this much simpler. When an object's back is horizontal, its hands and feet are often underneath the torso, making movement considerably more difficult.
This may not be the case, however, according to recent study that focuses on the fossilised Morotopithecus ape, which dates back 21 million years. Instead, scientists believe that early apes were leaf-eating creatures who inhabited a seasonal woodland with a broken canopy and open, grassy areas. According to the researchers, this scenery, rather than fruit in closed canopy forests, is what caused apes to stand upright.
Two studies that were just released in the journal Science reveal the findings.
According to senior scientist Laura MacLatchy of the University of Michigan, Because the trees were farther apart, it was believed that our forebears had to walk on two legs. After demonstrating that suchThe apes’ molars, which had multiple peaks and troughs, were the first indication that these extinct primates were consuming leaves. Unlike molars used for chewing fruit, which are normally more rounded, teeth required for breaking up fibrous leaves have molars like this one.
In addition, the tooth enamel of other animals located in the same stratum as the apes was investigated. In their teeth enamel, they discovered that isotopic ratios—the frequency of two isotopes of the same element—proved that apes and other animals had been consuming so-called C3 plants, which are now more prevalent in open woodland or grassy woodland habitats. In contrast to so-called C4 plants, which are largely arid-adapted grasses, C3 plants are primarily woody shrubs and trees.
Until recently, scientists thought that equatorial Africa was covered in dense forest around 20 million years ago, and that seasonal open woods and grasslands only appeared much later. The plant structure from nine fossil ape sites across Africa, including the eastern Uganda site, was nonetheless reconstructed in a second article headed by researchers at Baylor University using a set of environmental proxies. C4 grasses were widespread in the previous time period, according to these proxies. That suggests that these were all open, non-forested landscapes.
"The isotope data from the ancient plant waxes and phytoliths collected from the Morotopithecus site provide strong evidence for C4 grasses on the landscape at the local scale," said Kevin Uno, a paleoclimatologist at Lamont-Doherty and a coauthor of both articles. Other regional plant wax records from marine cores show that C4 grass is currently rare to nonexistent in eastern Africa. We now have a new challenge to solve, which makes this new data exciting: "Why do we see different signals at the local versus regional scale?"
The researchers employed carbon isotope measurements of old to recreate the ancient ecology there. The carbon isotope tests showed that a variety of plants, from those that form closed canopy to forested grasslands, were present in the grasslands.
The wax biomarkers—substances left over from the waxy coating that shields leaves—were examined by Uno’s team at Lamont. These showed a wide variety of grasses, shrubs, and trees. The oldest indication of C4 grass-dominated ecosystems in Africa and throughout the world dates back more than 10 million years thanks to phytoliths, tiny biosilica substances that give plants their structure and a defence against being eaten.
programme director for biological anthropology at the National Science Foundation, which supported the research.