Early homo most likely became progressively more daring
and aggressive at taking prey away from at least some of the smaller hunting and scavenging animals.
Genetic mutations that happened in the hominin lineage
MYH16 = regulatory gene mutation.
MYH16 (myosin) is a gene that moderates jaw muscle strength.
Less strong jaw muscles in early
hominins allowed selection for more gracile jaws and cranial lateral expansion.
There is interplay between tool use, increased protein in the diet
and relaxed physical constraints on cranial expansion (brain size increase).
Read the abstract on MYH16 mutation in the Unit 3 resources on the class website.
Different phylogenies have been suggested for the lineal connections between early hominins, but there is no consensus among anthropologists.
Different trees can be constructed, depending on which derived characteristic(s) the researcher includes in the comparison.
Homo erectus appears in the fossil record at about 1.8 mya and continue to be present in fossil records in Africa, Western, Central and East Asia
to about 1 mya (possibly surviving in remote locations until 25,000 y.a. or later).
Very early H. erectus overlaps the latest dates for H. habilis, so
it is unlikely that there is an ancestor-descendant relationship between these two species.
H. erectus was much taller than H. habilis, with long legs and post-cranial proportions of modern humans.
(H. erectus = more modern-human
looking post-cranial morphology than H. habilis.)
H. erectus bones are considerably more robust than those of
H. erectus legs are much longer than arms (as opposed to long-
armed H. habilis) and rib-cage is flatter, less “bell” shaped than H. habilis, but not as flat as the modern human rib-cage.
H. erectus had well
developed feet and hands, facilitating efficient bipedalism and manual dexterity for making finely crafted stone tools.
Skull and teeth
Long, low, thick-boned cranium.
Prominent supraorbital torus and receding forehead.
Pronounced occipital torus (underside back of the skull)
shows evidence of large neck muscle attachments.
Sagittal keel (slight ridge on the top of the skull, running from front to back) on most
Considerably less postorbital constriction than Australopithecines, but still present (low forehead).
Cranial capacity ranges from 700
– 1200 cc, with an accepted average of about 900 cc.
Robust mandible, no chin
“Shovel-shaped” incisors similar to those found in some
modern H. sapiens populations.
Illustrations of cranial features of H. erectus on pg. 350.
Compare cranial features in figure 12.7 on pg. 351:
H. erectus and H. sapiens.
Nariokatome Boy (KNM-WT15000):
the most complete specimen of H. erectus found to date.
Found in 1984 on the western side of Lake Turkana (formerly Lake Rudolph) in Kenya.
Dated to 1.6 mya, robust but surprisingly modern pelvis