Top 10 Human Ancestors

About 14 million years ago, the ancestral lines of the great apes began to split off from our own. The great-grandfolks of orangutans, then gorillas, and later chimpanzees all struck out on different evolutionary paths. Nakalipithecus nakayamai is the last known common ancestor of gorillas, chimps, and humans. Living ten million years ago in East Africa, it was a large ape somewhere around the size of a female gorilla. The discovery in 2005 of its jawbone and teeth in Kenya supports the view that our evolution took place wholly in Africa, rather than moving to Europe and back as had been speculated before.

Experts aren’t sure when exactly chimpanzee and human ancestors diverged. But the discoverers of Sahelanthropus tchadensis, a species that lived seven million years ago in Central Africa, believe it to be a transitional species from around the time the chimpanzee lineage branched off. So far, the fossil evidence consists mainly of one small, distorted cranium, and the details are debated. Was it arboreal or bipedal? Did it come before or after the split? Or was it an offshoot of another line entirely? Experts disagree, but the skull seems to combine both ape-like and human-like characteristics.

Some four million years ago, our curious great-grandfolks climbed down from the trees to poke about on the ground. Their forests were dwindling as the climate became cooler and drier. A few scientists think that supernovae also played a role, with radiation triggering lightning storms and forest fires that created more grasslands. Fossil remains of Ardipithecus ramidus, unearthed in Ethiopia and dated to 4.4 millions years ago, seem to show the transition towards bipedalism in action. The species had a big toe ideal for grasping branches, but also a pelvic structure that may have allowed them to walk on two legs. According to some researchers, its smaller canine teeth might suggest a reduction in aggression foundational for cooperative social behaviour.

Meet “Lucy”: one of the most famous fossils in history. In 1974 researchers found her three million year old partial skeleton in the Awash Valley in Ethiopia. To celebrate, they played the Beatles song “Lucy in the Sky with Diamonds” - inspiring her name. Lucy had long arms, a small brain, and a protruding jaw; but her pelvis was remarkably human, showing she could walk upright. It’s thought that others of her species left remarkably well-preserved at Laetoli, Tanzania, as they trekked through the muddy ash left by volcanic eruptions.

Lucy’s younger cousin Australopithecus africanus holds a special place in archeological history. In 1924, quarrymen stumbled over its fossilised remains in South Africa, catching the attention of Australian anthropologist Raymond Dart. Dart’s claim that the fossil was the so-called “missing link” between man and apes set him against many of his peers, who thought modern man must have jolly well come from Europe and not Africa. It took decades, but Dart was eventually vindicated. Modern analysis reveals that the fossil, which became known as the “Taung Child”, may have been killed by a hungry eagle. Ancient times were rough!

As the climate continued to cool and dry out two and a half million years ago, our ancestors faced new challenges. Grasslands replaced forests, and old food sources became scarce. Around this time, Homo habilis, the earliest known archaic human, began strolling the savannah. Meaning “handy man”, its name refers to its use of stone tools, possibly to butcher animals. The increased meat consumption may have driven other changes in our evolution. Homo habilis had a flatter face and larger brain than Australopithecus, although some scholars argue the line between them gets pretty blurry. But its emergence marked a huge step toward the evolution of modern humans.

Soon a taller and more slender species was also strolling the savannah: Homo erectus, aka “upright man”. Homo erectus is the earliest hominin believed to have mastered fire and to have cooked food, allowing a dramatic improvement in our ancestors’ diets. It’s commonly thought that Homo erectus originated in Africa two million years ago, then spread out through Eurasia. However, an origin in Asia has also been argued. Another point of contention is its relationship to Homo ergaster - which some consider a separate species, and others “African Homo erectus”. Regardless, it’s pretty humbling to think that Homo erectus survived for over two million years - making our own three hundred thousand year history seem like the blink of an eye.

We owe a lot to Homo heidelbergensis. If Homo erectus is our slightly eccentric grandfather, Homo heidelbergensis is closer to a familiar father figure. While it’s thought that Homo heidelbergensis descended from African Homo erectus, their time on Earth overlapped for several millennia. Arriving on the scene six to seven hundred thousand years ago, Homo heidelbergensis looked a lot like us, with a large brain and similar stature. They also built permanent shelters. Some fanned out throughout Europe, and eventually evolved into Neanderthals; a few ready travellers branched out into Asia, evolving into Denisovans. Meanwhile, back in Africa, there emerged a new species, possibly from Homo heidelbergensis: Homo sapiens.

We don’t know much about the Denisovans, Neanderthal’s eastern cousins. The only fossils we have are a few bones and teeth. But thanks to DNA analysis, we do know this: our ancestors had a pretty crazy sex life. And we don’t mean with each other. We mean with other species of humans. Denisovans branched off from Neanderthals, but also did the dirty with them, with us, and at least one other species, possibly Homo erectus. In fact, today’s Melanesians and Australian Aboriginals still carry traces of their DNA, and Tibetans might owe a gene that allows them to live at high altitudes to the same source.

Life for our ancestors could certainly be “nasty, brutish, and short”. How did they cope in a world where nature was unpredictable, and death sudden? Archeological evidence suggests that Neanderthals might have been the first humans to bury their dead, and may have even held funerals. It’s hard to say if this means Neanderthals had spiritual beliefs. But we do know they were much more sophisticated than once thought, using fire, advanced stone tools, and possibly language. Neanderthals may even have painted cave art in Spain. Stockier, stronger and bigger brained than us, they nonetheless vanished about 40,000 years ago, soon after modern humans reached Europe. But thanks to interbreeding, Neanderthal DNA lives on: carried in the genomes of homo sapiens today.