I learned this today. Depending on who you ask and what fossils you look at and what you define as “human”, there have been between eight and twenty-one different species of human on this planet. All but one of them are now extinct.
If you are like me, you probably think of ancient homo sapiens as having to compete with Neanderthals, slowly wiping them out, and becoming the only species of human. I was surprised to learn that there were actually a lot more species of “human”.
It is difficult to give a definitive answer to this question because some species are known by a very few fossils and new fossils are being found all the time.
The Smithsonian Institution lists 21 different species, so let’s have a look at some of those.
Ardipithecus kadabba. They lived about 5.6 million years ago. They evolved into Ardipithecus ramidus who lived about 4.4 million years ago in Ethiopia. They were able to walk on two legs and they could also live in the trees. They were quite light and had a small brain. They probably climbed trees to find food.
Australopithecus afarensis. They lived between 3.85 and 2.95 million years ago. Fossils from over 300 different individuals have been found. They were small. Males grew up to 151 cm and females up to 105 cm. They had a flat nose and a strongly projecting lower jaw, similar to modern apes. Their brains were about 500g, and they had strong arms and curved fingers for climbing trees. They were also adapted to walk upright.
Australopithecus africanus. They lived about 3.3 to 2.1 million years ago. They were smaller and lighter than the Australopithecus afarensis but they were similar in most other ways. Their foot and leg bones show that they walked upright, but their arm and hand bones show that they also climbed trees. The wear on their teeth show that their diet was similar to that of chimpanzees.
Australopithecus anamensis. They lived from 4.2 million to 3.8 million years ago. Their ankle joints show that they regular walked upright on two legs, but their arms were still adapted for climbing. Australopithecus garhi. They lived about 2.5 million years ago. Their femur is longer than previous species of early human, which means they walked upright and their strides were longer. Their fossils have been found near stone tools. They may have been the first species to use stone tools.
Australopithecus sediba. They lived about 1.98 million years ago. Complete fossil skeletons have been found. These skeletons show that Australopithecus sediba had the teeth, arms, upper chest, and legs for their ancestors, but the lower chest and some tooth traits of humans. They had a far more human-like gait. Their pelvis is adapted for upright working and they appear to be the transition from living in the trees to living mainly on the land. Interestingly, they turned their feet inwards when they walked and put their weight on the outer edge of the foot. This may show that walking upright evolved in several different ways.
Homo erectus. They lived between 1.9 million and 100,000 years ago. They are the earliest humans to have the same body proportions as us. They had the ability to run and they had a larger brain. They were the first humans to develop hand axes and other refined stone tools. Their large brains required more energy, which meant meat, which meant hunting. The earliest evidence of hearths and food cooking comes from this period.
Homo heidelbergensis. They lived between 700,000 and 200,000 years ago. They were a little shorter than we are and they were the first early humans to live in cold climates. They had short and wide bodies, which was an adaption to conserve heat. They definitely used fire and they had spears for hunting. It was also the first human to build shelters. They lived in social groups.
Homo neanderthalensis. They lived between 400,000 and 40,000 years ago. They are our closest relative. Their brains were larger than ours and they were adapted for living in cold climates. They hunted, made shelters, lived in groups, wore clothing, used tools, controlled fire,
Homo sapiens. That’s us. We have lived from 300,000 years ago. These are only a few of the examples that the Smithsonian Institute talks about. Some of these species are connected to each other and some are not. There are more species than are here and there are more species being found all of the time. Obviously, more is known about the more recent species than the ones that lived millions of years ago. It is interesting to think that early Homo Sapiens existed with several other species of humans. Did they compete? Did they intermingle? Why has our species continued while the others have disappeared? so many questions. That is something I will have to learn another day.
So, there have been many different species of early human and they all had different traits. By looking at them, it seems possible to make a timeline of important steps from then to now. And this is what I learned today.
Photo By Gerbil – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4533480Sources:https://humanorigins.si.edu/evidence/human-fossils/specieshttps://humanorigins.si.edu/evidence/human-fossils/species/ardipithecus-kadabbahttps://humanorigins.si.edu/evidence/human-fossils/species/ardipithecus-ramidushttps://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-afarensishttps://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-africanushttps://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-anamensishttps://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-garhihttps://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-sedibahttps://humanorigins.si.edu/evidence/human-fossils/species/homo-erectushttps://humanorigins.si.edu/evidence/human-fossils/species/homo-heidelbergensishttps://humanorigins.si.edu/evidence/human-fossils/species/homo-neanderthalensis