Links: Noisy Soils, First Art, Mars Geology

A few readings for your perusal.

1) Biologists are poking senors into soil to listen to the hum of life. Amazing article by Ute Eberle on what we can learn from acoustic signals given off by animals living within a soil profile.

Life in the soil was thought to be silent. What if it isn’t?

2)  When was the first 'árt' made? Is there a neat sequence from abstract scratches on rock and bone to representational art that adorns the walls of caves? Excellent article by Amy McDermott on this question, bringing together the viewpoints of archeologists and cognitive scientists. 

What was the first “art”? How would we know?

3) One year on, NASA's Mars Perseverance has been drilling into rock, collecting samples and finding some surprises along the way. It will now head towards an ancient delta to look for past life! Alexandra Witze reports on the progress.

A year on Mars: How NASA’s Perseverance hit a geological jackpot.

 

Imagination And Art In The Cave Of Forgotten Dreams

Filmmaker Werner Herzog got a once in a lifetime opportunity to enter the Chauvet caves in France which has some exquisitely preserved rock paintings, dated to about 30 thousand years ago. He made a 3D movie of the interior of the cave.

On Fresh Air he talks about his experience:

GROSS: And they wanted you to keep on the walk so that you didn't contaminate the rest of the cave, yeah.

Mr. HERZOG: Oh, you never - can never touch anything. It's not just contaminating. There are footprints, fairly fresh footprints. You do not want to superimpose your print of your hiking boot upon it. There's...

GROSS: Oh, over the cave-bear print. Yeah. 

(Soundbite of laughter) 

Mr. HERZOG: Yes, you just don't do this. And there's a footprint of a child, maybe eight-year-old, this very mysterious. We couldn't film it. We were not allowed, because it was deep in the recess of the cave.

The mysterious thing is that next to this footprint, probably a boy, probably around eight years old, parallel to it runs the footprint of a wolf. And I was very, very puzzled: Did the wolf stalk the boy? Or did they walk together as friends? Or did the wolf leave its footprints 5,000 years later? It's stunning. The lapse of time is completely and utterly stunning.

 
What a context for an artist to let loose his imagination! The Cave of Forgotten Dreams indeed.. but also the Cave of Infinite Imagination.

Werner Herzog also recently joined physicist Lawrence Krauss and author Cormac McCarthy in a conversation about how science and art inspire each other. Speaking about the differences between art and science Krauss remarks:

Science is imagination in a straitjacket.

Not quite so for the artists in the Cave Of Forgotten Dreams.

Listen / Transcript

Ancient Homo Leaves "Modern" Footprints

This has been covered by a lot of news agencies. I got my first look at these ancient human footprints found in Ileret, Kenya from my Economist.com sci/tech feed.


Credit: Brian Richmond/George Washington University

They look human and the research done using detailed measurements of the depressions and swells that are left when a foot presses on soft mud indicates that the creature walked pretty much like we do. Or at least they are very different from the Laetoli footprints found in Tanzania and interpreted to be made by a member of the Australopethicines about 3.75 million years ago. Those footprints suggested a gait that was more ape like. This one seems a more heel to toe style of walking closer to us recent humans. The sediment has been dated to about 1.5 million years old. The footprints indicate a stature and body mass consistent with Homo erectus.

I just wanted to point out something about the tempo of human evolution. In the figure below which shows the changes in cranial capacity seen in the human lineage I have marked the appearance of the modern bipedal gait as suggested by this study to compare the timing of its first appearance with the trend in the evolution of brain size.

Original Source: Nick Matzke

Our modern style of walking appeared well before our brain size reached modern proportions. This shows nicely one of the more important principles of evolution, that different traits within a lineage often evolve at different rates.

The collection of traits - anatomical and behavioral - that define us "modern" humans evolved over a long period of time ... out of step with each other (no pun intended!), the modern style of bipedalism preceding an increase in brain size to the present proportions by more than a million years.

So, there never was any one instance during our evolution when we can say we became modern humans.

When thinking about evolution I don't like the term "modern" humans. It has a teleological feel to it, that somehow evolution was directed towards building us. People use the term to mean that evolution is something that changed our ancestors in the remote past and that once all the pieces of anatomy and behavior feel in place in the Pleistocene, we Holocene "modern" humans haven't changed at all. It's those ancestors of ours who walked funny and could not talk or create art. There is a finality with which we seem to see ourselves.

Now that is simply not true. There is a growing body of evidence most recently compiled in a book by Gregory Cochran and Henry Harpending " The 10,000 Year Explosion" that suggest that the pace of human evolution since the advent of agriculture has in fact quickened.

One million years from now if our species still exists, our descendants will look back to us as an ancient form of human, a population "intermediate" between Homo erectus and themselves - Homo sapien syntheticus? - Evolution has changed us and will continue to do so in ways we cannot entirely predict.

Maybe thinking ourselves as "modern" just reflects our inability to anticipate what we might become in the future.

What Does It Mean To Be Human?

What does it mean to be human was one of the panel discussions at the 2008 World Science Festival in New York City. Anthropology.net had a post some time back reviewing that discussion. The panel pundits were a collection of eminent psychologists, geneticists, anthropologists and neuroscientists among many other fields. Each expert gave an opinion of what makes humans unique, in the sense of possessing a unique biological property. Most of the answers focused on various aspects of our cognitive abilities and for good reason since we seem to differ qualitatively in our ways of thinking and communication from other animals. Almost all the answers were rejected by the blog author, who gave examples of similar traits being present in various species of apes and birds. The post is worth reading. I was left thinking, so okay just what is it that makes us different? Maybe the difficulty arises because of the insistence of the term unique. That carries the burden of showing that we posses something that absolutely does not exist anywhere in the animal kingdom. This approach will likely fail, since our characters are ultimately derived from an ancestral condition and echoes of human-like properties are bound to exist in related groups. Besides evolution can be strongly convergent. Evolution comes up with similar solutions to deal with similar problems. Even in groups such as birds which are only distantly related to us, cognitive properties similar to our own, such as anticipation and deception have been shown to exist, a result not due to shared ancestry but due to convergence.

I am trying to think of what evolutionary trigger could have lead to the considerable differences in cognition that have accumulated between humans and our closest relatives. If I was to thrown my opinion in the ring I would go for neoteny , which is the retention of juvenile features in adults due to a slowing down or delay in development. The main consequence in humans of developmental delay has been a prolongation of helplessness in infants and an extended childhood. Some say we, especially the men, never really grow up, but there is a deeper evolutionary reason for it! Having helpless infants and inquisitive children in early human groups would have had radical consequences on group dynamics and given rise to different selection pressures on different sex and age groups. Sexual selection for intelligence in harsh habitats is one of the favoured explanations for the rapid rise of our cognitive abilities but that is consistent with a children centric scenario. Women may have selected men more capable of acquiring food and with more tolerant temperaments , ones likely to stick around and help out with the kids, giving rise to the now familiar system of pair-bonding. Another consequence would be an increase in group size, these social changes setting up evolutionary pressures for more complex forms of communications and signalling. As tool use became an intergral part of human life, children too would have come under selective pressures for skills and abilities to use tools and communicate what they have learned. As we grapple with the problems of economic growth, "knowledge economy" has become something of a buzzword. But humans have always been experimenters and innovators and evolution of a distinct life-history characterized by a long period of learning most likely played a big role in fuelling selection for and reinforcing these cognitive traits. In this sense we have always been knowledge based societies with a high premium placed on innovation, communication and information sharing. Neoteny is again not unique to humans. Within primates, apes in general are the most neotenous. Within mammals, primates in general are the most neotenous, and mammals tend to be more neotenous among terrestrial animals. This is not a rejection of neoteny being a special feature in our evolution, merely an acknowledgment that evolution works by remolding, re sculpting, exaggerating and recombining pre-existing traits. Evolution is descent with modification and not descent with "poof, where did that come from?".

In trying to make a list of what make us unique, I felt too much attention of the panel was on the what is now unique/very very different and not on how we got there. I accept the panel's agenda might have been restricted to the here and now but maybe it does make sense to take a longer view. What I mean is that all humans share an evolutionary history and uniqueness lies in the particulars of the evolutionary pathway taken by the human species, a trajectory followed only once in the 4 billion years or so of life on earth. Whatever our differences, genetic and cultural, what we do share is a history, one that is not shared with any other species, and that it is this history that we can use to differenciate ourselves from other species. And that applies equally to all other creatures as well. And so just what could be the particular shared history, the longer view that I referred to? Competition and adaptation take place in an ecological context and I like Jonathan Kingdon's explanation of what makes humans so different. He calls us "niche thieves", who through superior use of technology have gradually expanded out of habitats that we were originally biologically adapted to. Throughout our evolutionary history human populations have progressively encroached upon the habitats of competing species, driving many including other hominid species to extinction. Our biological evolution since the advent of complex tool use more than 2 million years ago has been keeping pace with and sometimes falling behind new cultural practices and our tool driven expansion into evolutionarily unfamiliar habitats. I like this definition because it is a constant reminder that we are an invasive species, one that has appropriated resources with total impunity. But it is also a reminder that with command and control comes the responsibility of managing these resources in a sustainable way. Our abilities to displace other species and take over resources has deep evolutionary roots. But evolution has also given us the mental make up to override these impulses and fix past wrongs. Maybe that's what makes us unique.