Hobbits hunting tiny elephants. Cavemen hunting each other. Science can tell us
a lot about our past — namely, that it took plenty of trial and error to get
modern humans. Here's what we know about some extinct human species and how they differ.
"The dawn of civilization. Primitive. Dangerous. Exciting. Wet."
Australopithecus represents the immediate ancestors of humans. There were several
Australophithecus species, but perhaps the best known is Australopithecus afarensis.
According to London's Natural History Museum, this species lived between 3.7 to 3 million years
ago. What makes them so famous to us was Donald Johanson's discovery of one of their skeletons
in 1974. That might not ring any bells, but if we said this was the ancient woman named Lucy?
That's her — and she was reportedly named after the Beatles song "Lucy in the Sky with Diamonds."
Afarensis were quite tiny. Their height ranged from between 3 feet, 2 inches to 5 feet, 5 inches
with a weight of between 55 to 141 pounds. Notably, males were much larger than females.
They had relatively small brains, too, when compared to modern humans. A very large
brained afarensis could have up to 550 cubic centimeters of gray matter. In comparison,
Livescience explains that modern human brains average 1,274
and 1,131 cubic centimeters for males and females, respectively.
Afarensis lived in East Africa, with fossils having been found in Ethiopia,
Tanzania, and Kenya. They lived a vegetarian lifestyle both in trees and on the ground.
Their faces were also more ape-like than human-like, with a forward jutting jaw,
and they actually had a lot in common with chimpanzees. While they could walk upright,
they were not fully adapted for long-distance travel on two feet.
When considering that afarensis lived for 700,000 years before going extinct,
it's not hard to conclude that the species was a pretty successful one.
About 2.5 million years ago, the global climate began to cool. An academic paper titled "Origin
of the Genus Homo" asserts that this may have been the spark that caused an Australopithecus
species to evolve into the first human species. The earliest known of these is Homo habilis,
which lived from approximately 2.3 to 1.4 million years ago in East and South Africa.
Unlike the preceding australopithecus species, habilis had completely evolved
for a bipedal lifestyle. They also had larger brains, at over 600 cubic centimeters.
Habilis were shaped differently, too. Their skulls were smoother and rounder compared to
australopithecus, their faces projected less, and their teeth were smaller and narrower.
Still, habilis were small compared to modern humans, averaging about 75 pounds. Their diet,
as it's explained by the Smithsonian, included hard to chew foods like woody plants. Habilis
also ate meat, which we know because of tool and bone evidence we've discovered.
That's right: These ancient ancestors invented, created, and used tools — In fact, this species'
name, Homo habilis, literally means "handy man." At the time of their discovery in 1964,
it was thought that they were the earliest users of tools. However,
it has been shown that australopithecus species may have been using tools earlier,
in a great example of how so much of prehistory is just sort of… up-in-the-air.
Homo habilis is often put forward as the ancestor of
all other human species… for better or for worse.
Homo erectus is well-known because a number of specimens of the species have
been excavated. These date from between 1.89 million to 110,000
years ago, making it the longest existing species of human ever.
According to the "Origin of the Genus Homo," erectus had larger bodies and smaller teeth
than Homo habilis. Also differentiating them from earlier human species were their
proportions. The Smithsonian reports that erectus had shorter arms and longer legs,
in similar proportions to modern humans.
Additionally, their height was comparable, ranging from 4 feet, 9 inches to just over 6 feet, with an
upward average weight of 150 pounds. Erectus were fully evolved to live a ground-based lifestyle.
What really differentiated erectus from earlier human species was brain size. Erectus' braincase
ranged from 700 to 1,300 cubic centimeters, far larger than their predecessors. Erectus
ate meat as well as plants, and used diverse tools that included handaxes and cleavers.
There were a couple of significant firsts for humans with erectus,
including the likelihood that they were the first to use and control fire. It's
also likely that a population of erectus gave rise to the lineage of modern Homo sapiens.
"The sun is in his hands!"
"No, no. It's fire."
"Where did it come from?"
"He made it."
One of the most debated human fossil finds is that of a Homo ergaster. As explained by Science Daily,
this species of human roamed eastern and southern Africa between 1.9 and 1.4 million years ago.
The argument over ergaster is whether it is its own separate species or if it is in
fact just a subspecies of Homo erectus. Many sources, such as the Smithsonian,
just lump ergaster and erectus together. Others, such as Michigan State University,
state that ergaster may have been the direct ancestor of erectus,
or that ergaster was just the version of erectus that lived in Africa. Another related controversy
is whether ergaster or erectus gave rise to the lineage that produced modern humans.
Because of the timeline, ergaster would have lived at the same time as erectus. However,
ergasters were more slender with thinner skull bones, while erectus were more robust. Ergasters,
like erectus, used tools and presumably had a similar lifestyle.
In 2003, on the island of Flores in Indonesia, scientists made a remarkable
discovery in the Liang Bua cave. As explained by National Geographic,
they found the remains of humans that stood about 3.5 feet tall and weighed at maximum 75 pounds,
though the females could be as light as 35 pounds. This species of human was dubbed Homo
floresiensis after the island on which they were found, but they were quickly nicknamed hobbits.
Smithsonian reports that this particular human species lived 100,000 to 50,000 years ago.
Floresiensis were diminutive. Their brains were about 426 cubic centimeters,
which is a little over a third of the size of a modern human brain. Despite the small
brain, floresiensis used weapons to hunt stegodon, a type of extinct pygmy elephant.
What scientists are trying to figure out is how floresiensis fits into our
family tree. Some believe that floresiensis descended from Homo erectus, while others,
as reported by Live Science, have suggested that they were modern humans who suffered
from mutations. Yet this is countered by skeletal differences, such as this species' lack of a chin.
The debate will likely only continue as more research and excavation is done.
As detailed by the Australian Museum, the first remains of this ancient human were
uncovered by archaeologists between 1994 and 1996 in Spain. However,
it hasn't served to make things clearer, and in fact, Homo antecessor is a hotly debated species.
Subsequent discoveries, also in Spain, have led scientists to date the species from 800,000
to 1.2 million years ago. This species was different from other human species,
with a selection of traits that clearly show that it was related to modern humans.
The brain size of antecessor, while large at 1,000 cubic centimeters,
was not particularly remarkable. Its height, which ranged from 5 feet, 2 inches to 5 feet,
9 inches made it very comparable to modern humans. Antecessor is thought to have led
a hunting lifestyle with large amounts of weapons and tools found at dig sites.
Also particularly interesting, says Live Science, is that the dig site and the remains
of ancient antecessor peoples came with another shocking discovery: The earliest evidence of
cannibalism. These early humans were, after all, easy prey — and decently nutritious.
Antecessors' facial features were definitely more modern than other early species,
as they included projecting noses and modern cheek bone structure. However, they also
had prominent brow ridges and a receding chin, features seen in other species of early humans.
All the same, these facial features, according to Britannica, have led some scientists to classify
antecessor as its own species. The Smithsonian reports that some have argued that this species
might have been the direct ancestor of modern humans, hence its name. Not everyone agrees,
and it's likely that the matter will not get settled until more specimens are found.
One of the largest archaeological findings of extinct humans was in the Rising Star
Cave System in South Africa. According to the Smithsonian, over 1,550 fossils representing
15 individual humans were recovered, and the species was dubbed Homo naledi.
Naledi lived from approximately 335,000
to 236,000 years ago. Curiously, naledi has many shared traits with Australopithecines,
such as the pelvis and shoulder. These are mixed with human traits, such as its hands and feet.
Even more intriguing is the brain. While Homo naledi's brain size was small, being reported
at no larger than 600 cubic centimeters, it was structured and shaped like a modern human
brain. What this indicates is that brain size may not matter as much as how it is organized.
There are many unanswered questions about naledi. The Australian Museum
says that there is no evidence of them using tools or fire. It's also
unclear what they ate, though marks on teeth suggest much erosion by grit.
Also unresolved is Homo naledi's relative place in the human genus. Did naledi exist
by itself for millions of years unchanged? Is it an offshoot of Homo erectus or is it
related to modern humans? If answers are to be found, they're still buried in the ground.
The most well-known of all extinct humans is Homo Neanderthalensis,
known popularly as Neanderthals. According to Britannica, Neanderthals first came on the
scene about 200,000 years ago and lived until as recently as 24,000 years ago.
The Smithsonian explains that Neanderthals are probably the closest extinct relative to modern
humans. They were smaller than modern humans, with males being about 5 feet,
5 inches tall at 143 pounds and females 5 feet, 1 inch tall at 119 pounds. However,
they were more robustly built, stronger, and had prominent noses.
All of these were adaptations for the cold, since Neanderthals lived from Western Europe
to Central Asia during the Ice Ages. To cope with these conditions, they had a slate of
advanced weapons and tools for hunting, gathering, and making clothes and shelter.
This intelligence is reflected in their brain size, which according to
Discover Magazine was about 1,410 cubic centimeters — larger than modern human
brains. Neanderthals also displayed culture, through what appears to be formal burials,
evidence of spiritual beliefs, and even possibly musical instruments.
The reason Neanderthals went extinct is debated, although it is likely they were
pushed out by modern humans. Still, recent genetic analysis shows that Neanderthals
interbred with modern non-African humans. So in a way, Neanderthals never really went extinct.
Very closely related to Neanderthals and modern humans are Denisovans. As
reported by The New York Times, this species is a recent finding from a cave in Siberia in 2010.
The initial findings, just a bit of a pinky bone and a wisdom tooth, seemed paltry. Soon,
other fragments appeared, mainly teeth and a jaw bone. However,
according to Nature, scientists were able to extract enough genetic material from
these miniscule raw materials to give us a picture of this species of human.
The working theory is that about 400,000 years ago, Denisovans branched off from Neanderthals
and that instead of migrating to Europe, they moved through Asia.
Denisovans were similar to Neanderthals in appearance, having broad chests and
low foreheads, but differed with wider skulls and jawbones. National
Geographic reported that like Neanderthals, Denisovans interbred with modern humans.
"This is forcing us to rewrite all the anthropology books,
that perhaps, it was sort of like Woodstock, 50-100,000 years ago."
For the Denisovans, this took place in New Guinea until at least 30,000
years ago — but potentially as recently as 15,000 years ago. If this is true,
then Denisovans were the last other human species to become extinct.