Early brain growth in Homo erectus and implications for cognitive ability

Abstract

Humans differ from other primates in their significantly lengthened growth period. The persistence of a fetal pattern of brain growth after birth is another important feature of human development. Here we present the results of an analysis of the 1.8-million-year-old Mojokerto child (Perning 1, Java), the only well preserved skull of a Homo erectus infant, by computed tomography. Comparison with a large series of extant humans and chimpanzees indicates that this individual was about 1 yr (0-1.5 yr) old at death and had an endocranial capacity at 72-84% of an average adult H. erectus. This pattern of relative brain growth resembles that of living apes, but differs from that seen in extant humans. It implies that major differences in the development of cognitive capabilities existed between H. erectus and anatomically modern humans.

A Female Homo erectus Pelvis from Gona, Ethiopia

“…Neonatal brain size was approximately 30 to 50% (the mean ratio is 34 to 36%) of early Pleistocene H. erectus adult brain size [~600 to 1067 ml (mean = 880 ml, n = 18 crania)] (21), an intermediate value between that of chimpanzees (~40%) and modern humans (~28%) (20). This new estimate of H. erectus neonatal brain size, in tandem with the revised age at death (~0.5 to 1.5 years) of the child's cranium from Perning (Mojokerto), Indonesia (<1.81 Ma) (22), suggests that H. erectus had a prenatal brain growth rate similar to that of humans but a postnatal brain and somatic growth rate intermediate between that of chimpanzees and humans (23).…”

“…Crystal structures, biochemical assays, and single-molecule analyses have suggested different modes of interaction between RT and nucleic acid substrates, providing snapshots of the nucleoprotein complexes that illuminate the functional mechanism of RT [e.g., (17)(18)(19)(20)(21)(22)(23)(24)(25)]. Nevertheless, how the enzyme-substrate complex acquires specific functional configurations and switches between different functional modes remains unclear.…”

“…Perhaps even more puzzling is how the dissociated RT locates the polymerization site during strand displacement synthesis, considering that the primer terminus may itself be displaced from the template by the competing nontemplate strand. Also, RT cleaves at many different sites within a DNA/RNA hybrid, but how it accesses these sites remains incompletely understood (21,22). A dynamic visualization of RT interacting with different substrates will help us address these questions and gain a more complete understanding of its function.…”

Relaxed genetic control of cortical organization in human brains compared with chimpanzees

“…brain evolution | plasticity | hominins | neocortex | altriciality C ompared with nonhuman primates, human brains are significantly enlarged, reorganized, and have a disproportionately expanded neocortex (1)(2)(3). The fossil evidence demonstrates that these changes occurred in the hominin lineage over the last ∼6-8 My (4-9) in parallel with modifications to neurodevelopmental rates (10)(11)(12)(13). Although some of these changes have been linked to certain genetic variants in the human lineage [either shared with other late hominin species or exclusive to modern humans (14,15)], exploring brain evolution in hominins is challenging because of the limitations of the endocranial fossil record (4,5).…”

The prehistory of compassion

“…Although life history models have suggested that this could be as old as the rise in meat consumption, the paleontological evidence tells a different story. Early Homo and Lower Pleistocene H. erectus display a more rapid development than extant humans (17)(18)(19). Perhaps the large-brained species of Middle Pleistocene hominins, which the Salé and SH14 specimens belong to, had already acquired most of the human pattern.…”