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Hyped ‘hominin’ headlines

Australopiths are in the news again


wikipedia.org, DurovaAustralopithecusafarensis-reconstruction
Australopithecus afarensis reconstruction displayed at Museum of Man, San Diego, California.

With the headline of a news item reading “Cranium of a four-million-year-old hominin shows similarities to that of modern humans” one might have expected a sensational finding. The study being highlighted examined the thickness of the cortical and spongy bone layers making up the flat bones in the roof of the skull. Reading the original paper (Beaudet, et al.),1 the main finding appears to be mostly about some australopithecines from Sterkfontein, South Africa having a high proportion of spongy bone in the skull. From this meagre finding, the researchers make the following leap in the media release:

“This large portion of spongy bone, also found in our own cranium, may indicate that blood flow in the brain of Australopithecus may have been comparable to us, and/or that the braincase had an important role in the protection of the evolving brain.”2

Notice the maybes, as well as ‘and/or’, in this statement, indicating that the researchers are hyping the importance of their finding. This is not unusual, as popular accounts such as what is released to the media are designed to evoke public support for ‘research’, put institutions on the map (attract funds and students), etc.

However, when it comes to evolution the hype can be excessive (see creation.com/reading-between-the-lines), especially with the human evolution story. As for their findings, the proportion of spongy bone in today’s humans was less, and considerably less in most instances. For example, the proportion (%) of spongy bone layer along the parasagittal section was 65.3, 83.3 and 81.6 (mean of 76.7) in three different australopithecines, compared to a mean of 55.2 in 10 extant humans. Hence, the proportions of spongy bone in these australopithecines and ‘us’ are not the same, as the above statement could be taken to imply. However, even if they were, so what?

What seems more revealing, when looking at the research paper, is the inconsistency in age dating of the main specimen (StW 578). Deposits in the Jacovec Cavern, where it was found, have been dated to around 4 Ma (million years ago), but also to 0.133 Ma, the latter date being ‘conveniently’ explained away. This illustrates the reality that there are no absolute ‘dates’; they are chosen on the basis of an acceptable evolutionary story.

Published: 9 August 2018

References and notes

  1. Beaudet, A. et al., Cranial vault thickness variation and inner structural organization in theStW 578 hominin cranium from Jacovec Cavern, South Africa, J. Hum. Evol. 121: 204–220, 21 May 2018 |doi:10.1016/j.jhevol.2018.04.004. Return to text.
  2. University of the Witwatersrand, Cranium of a four-million-year-old hominin shows similarities to that of modern humans, https://www.eurekalert.org/pub_releases/2018-06/uotw-coa062518.php, 25 June 2018. Return to text.

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