A STEP IN TIME: The 1.5-million-year-old footprints discovered near Ileret, Kenya, were likely made by an ancient relative, Homo ergaster, as it walked along the muddy shores of a river amidst birds and animals.
Image: MATTHEW BENNETT/BOUMEMOUTH UNIVERSITY
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Freshly discovered trails of ancient footprints, left on what was once the muddy shores of a river near Ileret, Kenya, indicate that some 1.5 million years ago human ancestors walked in a manner similar to that of people today. The international team of researchers who analyzed the prints say that those who left them had feet that looked a lot like ours.
The prints were probably left by Homo ergaster, an earlier, larger version of the widespread Homo erectus, says David Braun, a lecturer in archeology at the University of Cape Town in South Africa and co-author of the study set to be published tomorrow in Science. This discovery "lets us know that they were probably just as efficient at walking upright as we are," he says.
Previous research has shown that human ancestors were perfectly capable of getting around on their hind legs 3.5 million years ago—and perhaps even earlier. But Braun says these prints reveal, for the first time, a very modern foot with a parallel big toe—unlike an ape's opposable digit that's easily curled for grasping tree branches. Homo sapiens proper are said to have emerged about 200,000 years ago.
Footprints can tell scientists a lot about creatures that a skeleton cannot. From them, scientists can learn about the gait, weight distribution and even the approximate size of those who made them. Braun says these prints were apparently made by pedestrians who stood just under five feet (1.5 meters) tall. A modern upright stride can indicate a lot about behavior, as well, says David Raichlen, an assistant professor of anthropology at the University of Arizona in Tucson, who cites long-distance walking and running as possible benefits of this adaptation.
"It really is a snapshot of time," Braun says. The preserved area also shows a wealth of animal prints, which gives more precise information about what creatures shared the space and time. Exhumed fossils can yield info on general environments; footprints can provide a glimpse into life over days rather than millennia. "With the footprints," Braun says, "we can almost certainly say these things lived in the same time as each other, which is unique."
It is much rarer to find footprints than bones, because conditions must be perfect for tracks to be preserved, according to Braun. In this case, the tracks were made during a rainy season near an ancient river just before that river changed course and swept a protective layer of sand over them.
The last major set of footprints, discovered in 1978 in Laetoli, Tanzania, were dated to about 3.6 million years ago. But those revealed a more ancient foot and gait, and it is still debatable whether those who made them had a stride more akin to humans or to chimpanzees, says Raichlen, who has studied the Laetoli prints.
The Ileret tracks were digitally scanned using a laser technique developed by lead study author, Matthew Bennett, a geoarchaeologist at Bournemouth University in Poole, England. Raichlen says the find gives people a rare view of those that have trod before. "It's important to think about what you're really getting: a glimpse of behavior in the fossil record that you wouldn't really get in any other way," he says. The research reveals "a moment in time when individuals are walking around the landscape. It sort of fleshes out and brings them back to life, in a way."
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9 Comments
Add CommentExcellent new evidence. The more data that accumulate, the more rock-solid our understanding of the distant past will be.
Reply | Report Abuse | Link to thisCan someone email this story to Sarah Palin? :)
Reply | Report Abuse | Link to thisIf the footprints look so much like modern footprints, how can we be so certain they weren't made by Homo sapiens?
Reply | Report Abuse | Link to thisBecause in many ways they look similar to modern footprints.
Reply | Report Abuse | Link to this...and in others they don't.
The rock they were found in has been dated. That's how they know the age of the prints themselves.
Reply | Report Abuse | Link to thisIt must have been a major thrill to find and identify! Wow!
Reply | Report Abuse | Link to thisan important step to know the approximate time of the exsitence of the human being
Reply | Report Abuse | Link to thisThese are remarkable and exciting new anthropological finds at Ileret, Kenya. Yet, these 1.5 million year old footprints are the footprints of a pre-human hominid, Homo erectus -- not our species Homo sapiens. What is particularly significant is that the 1.5 million year old footprints of this prior species are indicative of modern human foot anatomy. Homo erectus was evolved about 2 million years ago in Africa. Nariokotome boy (KNM-WT 1500), a missing link stumbled across in 1984 in Lake Turkana, Kenya by a team led by Richard Leakey and Alan Walker, is an example of Homo erectus or Homo ergaster 1.5 million years ago. That childs eye sockets were overshadowed by a brow ridge, a ridge of bone that gave the skull a glowering expression, and there was a low, receding forehead leading to a long and flat crown. The boy had a tall, thin muscular physique, suited for radiating heat from his body in equatorial Africa and chasing game on the open plains. Australopithecenes millions of years before this also were walking on two feet. It is not that people adapted to equatorial climates by becoming tall and slender, or that people adapted to cold climates by becoming short and stocky. Rather, the Force tailors peoples and species to their environments and conditions. Creation: Towards a Theory of All Things by John Umana (amazon). When it came to feet, though, there was no need to reinvent the wheel from the anatomy of Homo erectus. The feet you are walking around on today are essentially the same feet that these people had 1.5 million years ago. Did we evolve from Homo erectus? No, not directly. But we did evolve from another species that was evolved from erectus. Biological evolution and common ancestry are real and proved by the convergence of the sciences. Darwin and Wallace were correct in positing that all species descend from prior species. The question is, what triggers the evolution of a new species from a prior species?
Reply | Report Abuse | Link to thisGenetic drift, disruptive environmental selective pressures, long periods of continual mutations and the very incident of extinction can play a huge role in the arrival of new critters as biota race to exploit the niche gap left in the extinct's wake. These are likely most, if not all the "triggers"
Reply | Report Abuse | Link to thisTo often people thing in terms of life hopping from species to species. We do this out of our own nature, a need to categorize and organize things into groups, nature doesn't work that way, thats not how it went down.
In the case of humans, I never hear anybody talk about the possibility of man-kind playing a role within its own evolution,