[This was prepared for homeschool.]
Humans are classified as:
- Animals (we reproduce sexually, and we depend on other organisms for our food)
- Vertebrates (we have a spine)
- Mammals (we’re warm-blooded, have hair, and our females provide milk for their young)
- Placental Mammals (our females give birth to live young, but the young don’t go into a pouch)
- Primates (hands that grip, nails instead of claws, forward facing eyes for binocular vision)
- Anthropoids (larger brains, expressive faces; this group includes monkeys and apes)
- Hominids (even bigger brains, no tail; this group includes the great apes)
- Hominins (we’re bipedal; brains range in size from chimpanzee-sized to our own)
Human beings are classified as Homo sapiens, which means that we are of the genus Homo, and our species name is sapiens. Homo comes from the Latin word for man. The Greeks had a similar word called homos, which meant same. The Greek word for man was anthropos. The word sapiens comes from the Latin word for wise.
The human lineage is believed to have split from the chimpanzee lineage sometime between 5 and 7 million years ago.
The genus from which humans probably evolved was the genus Australopithecus, which means southern ape. Members of the genus Australopithecus are referred to as Australopithecines.
Based on the evidence found so far:
- The Australopithecines appear in the fossil record about 4 million years ago.
- They appear to have died out by about 1 million years ago.
- The first tool-making humans appear to have been Homo habilis, who appear in the fossil record about 2.5 million years ago.
- The first human species that appears to have ventured out of Africa was Homo erectus, sometimes referred to as Homo ergaster, individuals of which appear to have emigrated by 1.8 million years ago.
- Homo heidelbergensis appears to have evolved from Homo erectus, and appears to have been ancestral to both Homo sapiens and Homo neanderthalensis (Neanderthals).
- Both modern humans and Neanderthals first appear in the fossil record over 100,000 years ago: Neanderthals in Europe and southwestern Asia; and modern humans in Africa.
- Neanderthals appear to have died out as a separate group over 20,000 years ago.
- Genetic evidence has recently been uncovered that modern humans and Neanderthals interbred.
- There are gradual changes in human fossils from the early Homo sapiens to the people of today, and we are sometimes referred to as Homo sapiens sapiens (although that may be a lot more wisdom than we deserve credit for, judging from history).
- Our species is believed to have reached a state of behavioral modernity by about 50,000 years ago.
There is considerable debate in the scientific community regarding many points of human evolution, and future discoveries should shed more light on the subject.