Just in case you were wondering, humans are also subject to the forces of evolution and natural selection. Although we have somewhat removed ourselves from the more obvious selection pressures of nature that our ancestors, as outlined below, had to deal with, we are still no doubt evolving. Even though the “fittest” are not selected by saber-tooth tigers anymore, there are still pressures from sexual selection, environmental determinants, etc.
Wondering what evidence we have for human evolution? Wondering what age they are, what describes the fossils, where they were found, what are the proverbial “missing links”? Don’t worry baby birds, I’ll feed you…
Human Evolution Timeline: Pre-Australopithecine
Sahelanthropus tchadensis | age: 6 – 7 mya fossils found: nearly complete cranium, some fragments lower jaw & teeth brain size: 350 cc adaptations: ape-like, including small brain size, hominid features: brow ridges, small canine teeth location found: Chad, Central Africa notes: close to common ancestor of chimpanzees and humans in the human evolution timeline; unlikely to be bipedal |
Orrorin Tugenensis | age: c. 6 mya brain size: no cranium found fossils found: 13 fossils; partial femur, bits of jaw and teeth adaptations: unknown location found: Kenya, Africa notes: some indications of bipedality, but evidence is scant |
Ardipithecus ramidus | age: 5.8 – 4.4 mya brain size: approx. 400 cc (chimp-size) fossils found: 110 specimens, almost complete skeleton adaptations: canine teeth intermediate between earlier apes & A. afarensis location found: Ethiopia notes: bipedal forest dweller(!), Canines smaller, not pointed |
Ardipithecus kadabba | age: 5.8 – 5.2 mya brain size: no evidence fossils found: fragments, mostly teeth adaptations: smaller canines than apes (a feature of hominids) location found: Ethiopia notes: |
Human Evolution Timeline: Genus Australopithecus
Australopithecus anamensis | age: 4.2 – 3.9 mya brain size: unknown fossils found: tibia, lower jawbone adaptations: very likely bipedal, thick enamel on teeth (hominid characteristic) location found: Kenya, Africa notes: tibia shape indicates bipedalism |
Australopithecus afarensis | age: 3.9 – 2.9 mya brain size: 375 – 500 cc (large male–female size difference) fossils found: hundreds of fossils, fourteen partial skeletons, and footprints(!) adaptations: certainly bipedal, chimp-like skull, flat nose, no chin w/ human-like teeth, jaw between ape & human location found: Ethiopia, Tanzania, Cameroon notes: This is Lucy’s species; she’s an original, important “missing link.” |
Kenyanthropus platyops | age: 3.5 – 3.3 mya brain size: unknown fossils found: two partial skulls adaptations: small ear canals, small teeth like Homo rudolfensis (branch of Homo habilis) location found: Lake Turkana, Kenya, Africa notes: scientists disagree whether these skulls deserve their own species |
Australopithecus africanus | age: 3 – 2 mya brain size: 420 – 500 cc fossils found: partial skull, cranium, body & pelvis adaptations: fully human-shaped jaw, canine teeth reduced from afarensis, human-like pelvis location found: South Africa notes: everything seems clearly adapted from afarensis |
Australopithecus garhi | age: 2.5 mya brain size: ? fossils found: partial skull adaptations: ? location found: Ethiopia notes: some evidence for tool use, otherwise not much known |
Australopithecus aethiopicus | age: 2.6 – 2.3 mya brain size: 410 cc fossils found: “The Black Skull” and some minor fossils adaptations: baffling; small brain, massive face & very strong jaw location found:Ethiopia, Kenya notes: some say this is perfect intermediate between afarensis and boisei, limited information |
Australopithecus robustus | age: 2 – 1.5 mya brain size: 530 cc fossils found: many, mostly cranial and dental adaptations: body like africanus, but larger skull, molars, and massive face & brow ridge, small canines location found: South Africa notes: bones found w/ robustus fossils may have been tools, this line of hominids had strong jaws and huge molars for crunching rough food, then probably went extinct (no descendants in southern Africa) |
Australopithecus sediba | age: 1.95 – 1.8 mya brain size: 420 cc fossils found: two partial skeletons, most of cranium in juvenile adaptations: more Homo adaptations than any other Australopithecine, pelvis is particularly advanced for bipedality so that it may have been capable of running, and brain case is shaped more towards human location found: South Africa notes: New discovery, described in April, 2010; pelvis and leg indicate it’s bipedal; more recent than many Homo fossils, thus unlikely to be human ancestor; probable adult height 4’6″ for male, 4’2″ for female |
Australopithecus boisei | age: 2.1 – 1.1 mya brain size: 530 cc fossils found: many, mostly cranial and dental adaptations: may just be robustus location found: Tanzania, Kenya, & Ethiopia, Africa notes: used to be Zinjanthropus; an unlikely human ancestor, probably went extinct due to over-specialization with its huge molars and small canines; some make them Paranthropus boisei |
Human Evolution Timeline: Genus Homo
Homo gautengensis | age: 2 million to 600,000 years ago brain size: awaiting publication fossils found: partial skull, several jaws, teeth and other bones adaptations: bipedalism, further information awaiting publication location found: Sterkfontein Caves, South Africa notes: Very stocky! 3 foot tall and 110 pounds; bipedal tree dweller |
Homo habilis | age: 2.4 – 1.5 mya brain size: 500 – 800 cc fossils found: many adaptations: primitive face, smaller teeth than australopithecines, human-shaped brain, had “Broca’s area,” a section of brain we currently use for speech location found: Kenya & Tanzania, Africa notes: named habilis for tools found with fossils, may need to be more than one species, Homo rudolfensis is suggested in addition |
Homo georgicus | age: 1.8 mya brain size: 600 – 780 cc fossils found: thirty or so partial skulls & a partial skeleton adaptations: intermediate between habilis and erectus location found: Dminisi, Georgia (eastern Europe) notes: First hominids out of Africa, a huge surprise because they didn’t have the brains or tools of Homo erectus |
Homo floresiensis | age: 1.1 mya to 17,000 years ago (possibly 2 mya!) brain size: 420 cc fossils found: several almost full skeletons adaptations: dwarf hominim found on island; large feet, ape-like hands, small brain, similar features to H. habilis location found: Flores, Indonesia notes: dwarves of species commonly develop on islands, these were 3 feet tall; hunted dwarf elephants and large rats; new research on relative brain size suggests they descended from H. georgicus or habilis rather than erectus |
Homo erectus | age: 1.8 million – 300,000 years ago brain size: 750 – 1225 cc fossils found: lots and lots adaptations: jaw still protrudes, no chin, thick brow ridges, small forehead, but larger brains and excellent walkers location found: Africa, Europe, Asia notes: probably used fire, brains got larger over time |
Homo ergaster | age: same as erectus brain size: slightly smaller than erectus fossils found: these would be the African erectus fossils reclassified adaptations: taller & thinner & different-shaped brow ridges than European & Asian erectus fossils location found: Africa notes: some scientists make the African erectus fossils to be Homo ergaster |
Homo antecessor | age: 780,000 years ago brain size: 1000 cc fossils found: six individuals adaptations: mid-facial area modern, other parts primitive location found: Spain notes: oldest European hominids, may just be erectus or early heidelbergensis |
Homo sapiens or Homo heidelbergensis |
age: 500,000 years ago brain size: 1200 cc fossils found: many skulls adaptations: intermediate between erectus and human in thickness of bones & size of teeth, receding foreheads and chins location found: Europe notes: some scientists consider these the European version of Homo erectus; later ones are difficult to distinguish from early Homo sapiens; sometimes heidelbergensis is called Homo sapiens (archaic) in contrast to modern humans who are Homo sapiens sapiens |
Homo neanderthalensis | age: 230,000 – 30,000 years ago brain size: 1450 cc fossils found: lots and lots adaptations: midfacial area protrudes, long low brain case, thick & strong, near our height; many adaptations seem like adaptations for cold location found: Europe & Middle East notes: first hominids to bury dead, lots of tools & weapons, lived brutal lives; brain was larger than ours! |
Cro-Magnon (Homo sapiens)s |
age: 50,000 – 10,000 years ago brain size: 1350 cc fossils found: many adaptations: These are now classified as anatomically-modern humans location found: Europe notes: Our ancestors in Europe were thicker in tooth and bone than we are |
Homo sapiens | age: 195,000 years ago – 2009 brain size: 1350 cc fossils found: living samples available in large quantities adaptations: forehead rises sharply, small or non-existent brow ridges, prominent chin, thin skeleton location found: everywhere notes: tooth and face bone size is still decreasing over the last 20,000 years of the human evolutionary timeline! |
Thank you for reading!
Thanks, great article.