Middle Pleistocene Man (Homo heidelbergensis)

Many late Pleistocene animals evolved from middle Pleistocene ancestors that were different enough to be considered separate species.  Columbian mammoths (Mammuthus colombi) evolved from the southern mammoth (M. meridionalis), a shorter elephant with straighter tusks. Jefferson’s ground sloth (Megalonyx jeffersoni) evolved from Wheatley’s ground sloth (M. wheatleyi), and Smilodon fatalis evolved from the more lightly built S. gracilis, among many other examples.  The same is true for humans.  Both Homo sapiens and H. neanderthalis evolved from H. heidelbergensis, also known as Heidelberg man after discovery of the first specimen in Heidelberg, Germany during 1907.  Genetic evidence suggests modern humans diverged from Neanderthals between 750,000 years BP-550,000 years BP.  The population of Heidelberg man that lived in Europe evolved into H. neanderthalis, while the population of Heidelberg man that lived in Africa evolved into H. sapiens.  (The poorly known Denisovans diverged from Neanderthals.) Fossil evidence of Heidelberg man dates to between 600,000 years BP-300,000 years BP, though undoubtedly it occurred earlier than the fossil evidence indicates.  The oldest evidence of humans in Europe dates to 800,000 years ago and was found in Spain, but these specimens are considered an extinct sister species of Heidelberg man known as H. ancessor.

Artist’s depiction of Homo heidelbergensis.  They were about the same height as modern men and had the same average brain capacity, but their jaws were distinctly different.

The Schoningen spears, 330,000 year old projectile weapons used by Homo heidelbergensis.  They were found in a strip mine in Germany.  Archaeologists found 9 spears, 1 lance, a stick pointed on both ends, and a burned stick along with the remains of butchered horses next to a lakeshore.

Heidelberg man evolved from H. erectus.  Heidelberg man had a more human-like face and a larger brain capacity (averaging 1200 cc compared to 973 cc).  They had the same average brain size as modern day humans, and the main difference between the 2 is the shape of the jaw which was distinct.  Heidelberg man was the first species of human to colonize regions with cold climates.  To survive in harsher climates, they evolved to eat more meat.  In Europe this diet included elephant, rhino, bear, deer, boar, and horse; and in Africa they ate antelope and zebra.  They surely ate many different kinds of plants, but nothing is known of the vegetal part of their diet.  Heidelberg man had control of fire and used tools such as stone hand axes and wooden spears. In 1994 nine spears made of spruce wood were found in a German strip mine, and they dated to 330,000 years BP.  They are known as the Schoningen spears, and they were found associated with butchered horse bones.  Rapid rise of a lake level covered all this evidence in sediment and helped preserve it.

I have no doubt Heidelberg man could speak, though a minority of scientific opinion believes they could not.  The hyoid bone, important for speech, is well developed as are the middle ear bones used for understanding speech.  There is also evidence for right brain/left brain lateralization–one side of the brain is more dominant.  Brain lateralization suggests a brain used to speak and understand speech.  Heidelberg man hunted large mammals, an activity requiring cooperative hunting and therefore speech.

Specimens of Heidelberg man have been found in sites located in Germany, England, France, Greece, India, Zambia, Kenya, Ethiopia, and South Africa.  I tried to find out exactly how many specimens have been discovered worldwide, but as far as I can determine no study has catalogued them all.

Heidelberg man likely occurred in low population numbers, fluctuating with boom and bust climatic conditions, and whole tribes often perished  when important members died.  One site in Germany where Heidelberg remains were found also yielded bones of saber-tooths (Homotherium), lions, leopards, hyenas, bear, elephant, red deer, and horse.  Unlike modern humans, Heidelberg man didn’t always win in competition with the predators they shared the landscape with.

Reference:

Schoch, W.; G. Bigga, W. bohner, P. Richter, and T. Terberger

“New Insights on the Wooden Weapons from the Paleolithic Site of Schoningen”

Journal of Human Evolution 89 December 2015

Advertisement

Did Neanderthals (Homo neanderthalis) really Interbreed with Humans (Homo sapiens)?

Warning: Do not read this blog entry, if you are younger than 18.  The nude images might cause blindness.

A new study published in the scientific journal, Nature, of a 40,000 year old skull suggests Neanderthals (Homo neanderthalis) interbred with humans (Homo sapiens).  This particular specimen, found in Romania, is thought to be 6%-9% Neanderthal, and the authors of this study think this individual had a great-great-great-great Neanderthal grandparent.  He left no living  descendants, but other studies of Neanderthal DNA determined Homo sapiens and Homo neandetheralis did hybridize, and some modern Europeans and Asians might be 1%-3% Neanderthal.  The media likes this story, and a study casting doubt on the assumptions used to identify past hybridization is being ignored.  I didn’t even see the study listed in the new journal article’s references, so the scientists involved in Neanderthal DNA studies are unaware of the article or are ignoring it as well.

The ignored study, referenced below, was written by A. Ericksson and A. Manica.  They write “tests for hybridization rely on the degree to which different modern populations share genetic polymorphisms with genomes of other hominins.”  A polymorphism is defined as 2 clearly different phenotypes existing in the same population of a species.  A phenotype is the composite of an organisms observable characteristics.  For example a population of humans could consist of big blondes and small brunettes–2 different phenotypes.  The authors of this study show that examples of shared polymorphism attributed to hybridization could actually have originated before H. neanderthalis and H. sapiens diverged over 200,000 years ago.  Both species of humans evolved from H. heidelbergensis.  The population of H. heidelbergensis that colonized Europe evolved into H. neanderthalis.  The population of H. heidelbergensis that stayed in Africa until ~45,000 years ago evolved into H. sapiens.  An Asian colonization evolved into the poorly known Denisovans.

The authors of this study believe their findings don’t rule out the possibility of hybridization in Europe, but they urge “caution” when making the assumption that hybridization occurred.  To determine whether or not the degree of shared polymorphism was the result of hybridization or was part of an earlier genetic pattern from the founding population structure would require DNA from a specimen pre-dating the divergence of these 2 species.  Viable DNA can’t be extracted from specimens that old.

Representation of a female Neanderthal based on DNA studies.  Note the red hair.  Neanderthals had red hair.

Nude female Homo sapiens.  Human women are much cuter than Homo neanderthalis.  Moreover, female Neanderthals were probably considerably stronger than male Homo sapiens.  I doubt the 2 species interbred.  Genetic studies can’t discern certain hybridization without studying the DNA of the ancestral common ancestor of both species.  This is impossible because those fossils are too old to harbor DNA.

I doubt H. sapiens bred with H. neanderthalis.  The 2 populations of humans had been isolated from each other for over 200,000 years.  Behavior patterns likely dramatically differed. Facial features were significantly different, and I think they didn’t recognize each other as mating material.  Neanderthals were intelligent ambush predators that used thrusting weapons, and they were physically more powerful than humans.  But humans were smarter and had developed projectile weapons.  Humans ate a wider variety of foodstuffs, contributing to greater fertility.  I think humans wiped out Neanderthals within a few thousand years.  Assimilation was unlikely.

Reference:

Ericksson, A.; and A. Manica

“Effect of Ancient Population Structure on the Degree of Polymorphism Shared between Modern Human Populations and Ancient Hominins”

PNAS 2012

http://www.pnas.org/content/109/35/13956.full