Archaic human parents had to look after helpless infants like modern day parents do, according to new research. Human babies are born less developed than those of other great apes, and so are unable to move as freely. A common result of this is deformational plagiocephaly, also called flat head syndrome. Professor Yousuke Kaifu at the University of Tokyo led a team which studied head shapes from scans of living infants, historical Japanese skeletal remains, fossilized specimens of Homo erectus and Homo floresiensis, and compared these to measurements of dry skulls from other great apes. Human head shapes across the ages, as well as the fossilized samples, exhibited a far wider range of deformation. The team sees this as evidence that archaic humans birthed helpless infants, with implications for childcare practices and potentially cooperative social behaviors dating back hundreds of thousands of years.

A new study documents a set of fossil footprints preserving a snapshot of “fossil behavior” from an ancient hominin group along a lakeshore in northern Kenya around 1.4 million years ago. An international team of researchers from the US and Kenya found tracks showing eight Paranthropus boisei individuals — an extinct “cousin” of modern humans — in one place at one time. All of the individuals are thought to be adults, and some appear to have been much larger in body size than previous estimates based on rare fossil bones.