OUR COMMON AFRICAN HERITAGE

OUR COMMON AFRICAN HERITAGE

James R. Fisher, Jr., Ph.D.

© December 15, 2011

We were all black before some of us were white.  That is the implication in Chris Stringer’s new book, “The Origin of our Species” (2011). 

There is little we don’t know about our remote ancestors by analyzing the chemistry of their bones, or by examining the structure of minute features such as the inner ear bones of fossil skulls by means of computerized tomography, or luminescence techniques to date single grains of sand.  Stringer’s mobile phone has more processing power than the multi-room University of Bristol computer he once used in the 1970s where he processed human fossils data with multivariate statistics, now a common tool for college freshman.

Over the last forty years, astounding advances have been made with Recent African Origin studies and multi-regional models resulting in new fossil discoveries and archaeological excavations, dating methodologies, and new procedures for the extraction of ancient DNA. 

The major players in our common African heritage are Homo erectus, the first human to disperse out of Africa sometime after two million years ago.

Homo heidelbergensis, a descendant of Homo erectus, is most probably the common ancestor of the Neanderthal man and us.

Homo neanderthalensis remains have been found in Europe and South-West Asia.  They appear so biologically similar and yet so culturally different from us that there still remains a gap to be explored and explained before Homo sapiens.  Once Homo sapiens arrived on the scene they populated the world first narrowly then more widely.

Springer charts the advances in our understanding of the fossil, archeological and genetic evidence before bringing all the evidence together in the most up to date synthesis available.  This is the main thesis of his book.

Genetics, both ancient and modern, is said to be impressive but to show little new light on what was already known of our ancient ancestors in terms of language, thought, symbolism and behavior.  One thing seems abundantly clear, Homo sapiens had a single origin in Africa around 200,000 years ago, and that the common human race, at that time, was black, all black with no white race yet to evolve.

The vast research now is into analysis and interpretation of the genetic diversity of living people not only in terms of what is called MtDNA, but also in terms of autosomal DNA.  The later makes up the chromosomes contained in the nuclei of our body cells, and the male Y chromosome.  Stringer describes the male Y chromosome as being boring and full of junk (DNA junk). 

Genetics are not expected to replace the analysis of fossil and archaeological remains, but it has already transformed the way researchers interpret these findings, and therefore is likewise expected to lead to an avalanche of studies in that respect.

Already, this research has led to the discovery of some fascinating details about Homo sapiens.  For example, blue-eyes were selectively evolved along with paler skin color in Europe around the peak of the last Ice Age, which appeared 20,000 years ago.

Springer warms that genetic diversity complemented by ancient DNA extracted from fossils must be interpreted with caution because of the small number, and size of the samples, and the risks of contamination by modern DNA. 

That said more than twenty Neanderthal specimens confirm that they probably shared a common ancestor with us between 350,000 and 500,000 years ago.  There is also strong evidence for some degree of interbreeding between modern humans and Neanderthals.  Stringer concludes, “If you are European, Asian or New Guinean, you probably have a bit of Neanderthal in your make up.” 

To corroborate this hypothesis, samples of Neanderthal DNA from skeletal remains in Spain and Italy indicate that southern European Neanderthals would have had paler (white) skin and red hair, which is a departure from the black skin and black hair of more common Neanderthal fossils. 

Surprises abound in Springer’s “The Origin of Our Species.”  No one expected to find “primitive” looking Homo erectus fossils at Dmanisi in Georgia in 1991, as it was assumed only larger-brained hominids could have dispersed from Africa.  Yet, in 2004, a fossil of a small-brained hominid with weird limbs was found in Flores, an Indonesian island, dating back 18,000 years.

Paleontologists-anthropologists have to live with the risks that new discoveries will overturn their most cherished theories.  Given the fossil record is so sparse, it is unfortunate that the Japanese destroyed the rich collection of Homo erectus fossils near Beijing during WWII. 

Mysteries remain, and fossil and archaeological evidence continue to turn up new discoveries.  For example, DNA of a molar tooth and finger bone from Denisova Cave in Siberia was dated 40,000 years ago, but it was not the DNA of Homo sapiens or Homo neanderthalensis, but of a completely new human species living in eastern Asia, and a derivative of Homo heidelbergensis, who lived well over 500,000 years ago.

Springer concludes that, in any case, these specie identifications are artificial constructs to approximate our understanding of the complexities of our human evolutionary process. He argues for Homo sapiens being African in origin dispersed in a global Diaspora around 55,000 years ago.  The human race evolved in its many complexions, body types, and structural differences many of which are now known, but many of which are not.  Climate, topography, interbreeding, and occupation have influenced these complexities of gradient differences.  What’s more, he claims we are still evolving.  The emergence of settled farming communities some 12,000 years ago produced selective new pressures influencing diet, adaptation, socializing, reproductive practices and sheltering schemes.  Changes in individual DNA sequences suggest human evolution has accelerated over the last 10,000 years.  We are evolving a hundred times faster than we were when we split from the lineage of chimpanzees around six million years ago. 

Springer concludes the most compelling model of our human origins, whatever our color, race, body type, heritage, is one of a common African origin.  Future science will either confirm or refute his hypothesis.

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