Human evolution: new discoveries in footprints (Introduction)

by David Turell , Wednesday, June 14, 2023, 00:06 (318 days ago) @ David Turell

A new review of the discoveries of sapiens footprints:

https://phys.org/news/2023-06-oldest-homo-sapiens-footprint-years.html

"In 2023 the situation is very different. It appears that people were not looking hard enough or were not looking in the right places. Today the African tally for dated hominin ichnosites (a term that includes both tracks and other traces) older than 50,000 years stands at 14. These can conveniently be divided into an East African cluster (five sites) and a South African cluster from the Cape coast (nine sites). There are a further ten sites elsewhere in the world including the UK and the Arabian Peninsula.

"Given that relatively few skeletal hominin remains have been found on the Cape coast, the traces left by our human ancestors as they moved about ancient landscapes are a useful way to complement and enhance our understanding of ancient hominins in Africa.

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"We found that the sites ranged in age; the most recent dates back about 71,000 years. The oldest, which dates back 153,000 years, is one of the more remarkable finds recorded in this study: it is the oldest footprint thus far attributed to our species, Homo sapiens.

"The new dates corroborate the archaeological record. Along with other evidence from the area and time period, including the development of sophisticated stone tools, art, jewelry and harvesting of shellfish, it confirms that the Cape south coast was an area in which early anatomically modern humans survived, evolved and thrived, before spreading out of Africa to other continents.

"There are significant differences between the East African and South African tracksite clusters. The East African sites are much older: Laetoli, the oldest, is 3.66 million years old and the youngest is 0.7 million years old. The tracks were not made by Homo sapiens, but by earlier species such as australopithecines, Homo heidelbergensis and Homo erectus. For the most part, the surfaces on which the East African tracks occur have had to be laboriously and meticulously excavated and exposed.

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"A key challenge when studying the palaeo-record—trackways, fossils, or any other kind of ancient sediment—is determining how old the materials are.

"Without this it is difficult to evaluate the wider significance of a find, or to interpret the climatic changes that create the geological record. In the case of the Cape south coast aeolianites, the dating method of choice is often optically stimulated luminescence.

"This method of dating shows how long ago a grain of sand was exposed to sunlight; in other words, how long that section of sediment has been buried. Given how the tracks in this study were formed—impressions made on wet sand, followed by burial with new blowing sand—it is a good method as we can be reasonably confident that the dating "clock" started at about the same time the trackway was created.

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"The overall date range of our findings for the hominin ichnosites—about 153,000 to 71,000 years in age—is consistent with ages in previously reported studies from similar geological deposits in the region.

"The 153,000 year old track was found in the Garden Route National Park, west of the coastal town of Knysna on the Cape south coast. The two previously dated South African sites, Nahoon and Langebaan, have yielded ages of about 124,000 years and 117,000 years respectively.

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"A decade from now, we expect the list of ancient hominin ichnosites to be a lot longer than it is at present—and that scientists will be able to learn a great deal more about our ancient ancestors and the landscapes they occupied."

Comment: a continuing support for the theory sapiens developed all over Africa. See the entry on HAR's, rapidly evolving areas of human DNA.