At the end of The Origin of Species, Charles Darwin wrote: “Light will be thrown on the origin of man and his history”. This is the only reference to our origins in the 502 pages of the 1859 edition of his book. The father of biological evolution was convinced that the world was not ready to receive the news of our kinship with apes and other animals. More than 30 years later, the German physicist Wilhelm Röntgen produced a new electromagnetic radiation in a wavelength range known as x-rays, an achievement that earned him the first Nobel Prize in Physics in 1901. Immediately some scientists realized that this new “light” could be used to fulfill Darwin’s prophecy.
One of these was the Croatian paleoanthropologist Dragutin Gorianović-Kramberger, who used x-rays to radiograph the remains of the Neanderthals discovered in 1899 in the Krapina cave. Today, new x-ray sources, such as synchrotron accelerators, are iIluminating the remains of Neanderthals and other extinct hominids. Novel microscopes provide 3D images for the inner structure of their teeth, skull and many other bones, revealing all their biological secrets. The microarchitecture of their teeth preserves a detailed record on the hominid life history, including the length of his childhood, which is critical for the evolution of cognitive capabilities. One can also virtually reconstruct the brains of different hominids from the x-ray images of the skull’s inner surface, tracing the evolutionary process that led to the development of the modern human mind.
We hope to understand why we became the ‘Masters of the Planet’ while other human species, like the Neanderthals and the Denisovians, who had lived for millennia side by side with our direct ancestor, H. sapiens – sometimes with intimate encounters – became extinct. Probably the secret lies in our capacity to become a social organism, thanks to the size and the peculiar structure of our brain cortex.
To shed light on our origins we need all kinds of “lights”: X-rays to read bones, skulls and teeth; laser-based dating techniques to synchronize archaeology, climate change and genetic clocks; and radar and other electromagnetic waves to find more fossil and archaeological evidence from the past.
Claudio Tuniz is a scientist of the Abdus Salam International Centre for Theoretical Physics in Trieste and Associate Scientist of the Enrico Fermi Center in Rome. In Australia he is Visiting Professor at the University of Wollongong and Visiting Scientist at the Australian Nuclear Science and Technology Organisation. He published Radioactivity, Oxford University Press, 2013, The Science of Human Origins (with G. Manzi and D. Caramelli), Left Coast Press, 2014, The Bone Readers (with R. Gillespie and C. Jones), Allen and Unwin, 2009, and Homo sapiens: una biografia non autorizzata (with P. Tiberi Vipraio), Carocci, in press.