In a tradition begun in 2009 – the bicentennial of Charles Darwin’s birth on February 12, 1809, and the 150th anniversary of the publication, in 1859, of the first edition of his book On the Origin of Species – Darwin’s birthday is celebrated annually in many academic institutions as International Darwin Day. The festive, worldwide celebration expresses humanity’s appreciation of Darwin for “opening its eyes” and for the upheaval he generated in the paradigm that had prevailed, in various forms, prior to the book’s publication. In 2017, the Israel Academy of Sciences and Humanities joined the celebration. We marked International Darwin Day in Jerusalem for the second time this year and hope to make it an annual tradition here, too.

 

This year’s Darwin conference at the Academy was devoted to the evolution of humanity’s special distinction – the human brain. This, indeed, was one of the first questions raised when the theory of evolution began to gain ground. Was there, as Darwin suggested, a connection between the development of the brain and walking upright, freeing the hands from bearing the weight of the body (another special distinction of human beings)? If so, when did this occur, and why? Is the uniqueness of the human brain solely attributable to its large size? Fossil evidence provides an easy answer to the first question. We know today that the transition to walking upright preceded the expansion in human brain size by millions of years, and their relationship therefore cannot be seen as a matter of cause and effect. It also became clear that brain size is a much more complex topic than early researchers had assumed. Another mystery pertains to the relatively sudden “takeoff” in brain size about 1.5 million years ago. Academy member Prof. Yoel Rak of Tel Aviv University opened the conference by addressing these questions in a lecture entitled “Buried in the Brains of Fossils.”

 

The archeological evidence that early hominids left behind – the material products of their brain activity – is almost the only thing that enables us to study what was buried in the brains of fossils. Reconstructing the design of tools they created indicates the extent of their brains’ complexity and the considerable sophistication of the technology they employed in creating these implements, especially in light of the physical limitations of the specific raw material they used – stone. Two fascinating lectures discussed this subject: “Planning, Learning or Raw Material: How Should We Understand the Stone Tools from 2.5 Million Years Ago?” by Prof. Erella Hovers of the Hebrew University, and “What Can We Learn from the Brain of Hominids Who Created Acheulean Culture?” by Academy member Prof. Naama Goren-Inbar of the Hebrew University, whose lecture focused on findings from a younger prehistoric site.

 

The human ability of speech is also closely connected to intellectual ability. Unfortunately, fossils cannot tell us when this ability developed, because the voice box (larynx) that produces the sounds of speech is entirely cartilaginous and thus does not fossilize. Dramatic developments in understanding the relations between phenotype and genotype, together with the ability to find DNA in fossils (so far, only in fossils that are relatively young geologically), shed light on this question as well. Prof. Liran Carmel of the Hebrew University lectured on new developments in this field and on the conclusions of his fascinating research. His lecture was entitled: “DNA from the Dead: What Do the Genetics of Our Ancient Ancestors Say about Our Ability to Speak?”

 

See you at the next International Darwin Day.