Neanderthals and the Origin of Life: Key Concepts
Neanderthals: A Closer Look
(7) Homo neanderthalensis
- They are closer to non-African than African anatomically modern humans, likely due to interbreeding between Neanderthals and the ancestors of Eurasians.
- Evidence of fire use by Neanderthals in Gibraltar suggests they may have survived there until 24,000 years ago.
- Neanderthal cranial capacity is thought to have been as large as, or perhaps larger than, that of modern humans.
- They were much stronger than modern humans, with particularly strong arms and hands. Males stood 164–168 cm and females about 152–156 cm tall.
- They had a chin displaced backwards, protruded eyebrows, a forward mouth, and a wider nose and chest, adaptations for colder climates.
- They cared for the elderly within their clan.
- Neanderthal fossils have not been found in Africa, but have been found close to Africa, in Gibraltar and the Levant.
- Neanderthals were better adapted to cold weather than modern humans and sometimes displaced them in the Middle East during colder periods.
- They were largely carnivorous, but new studies indicate they also cooked and consumed vegetables. They made advanced tools, had a language (the nature of which is debated), and lived in complex social groups.
Hypothesis for Extinction
They were a separate species that became extinct due to climate change or interactions with other humans. They were replaced by modern humans moving into their habitat around 80,000 years ago. Competition with other humans likely contributed to their extinction. Interbreeding may have occurred, explaining some similarities with modern humans.
About 55,000 years ago, the weather began to fluctuate wildly. Neanderthal bodies were well suited for survival in cold climates, with barrel chests and stocky limbs that stored body heat better than Cro-Magnons. An alternative to extinction is that Neanderthals were absorbed into the Cro-Magnon population through interbreeding.
The Origin of Life
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- Oparin (1924) Hypothesis of the primitive soup: CH4, H2, NH3 (inorganic matter) reacted, producing different organic compounds, catalyzed by UV rays (no ozone layer in the primitive atmosphere).
- Haldane (1928) reached the same conclusions.
- Miller’s experiment (1952) supported this hypothesis, demonstrating it was possible to generate organic compounds with a source of energy and inorganic matter.
- Some scientists believe that life came from outer space due to meteorites carrying bacteria (Panspermia Hypothesis). Anaxágoras, Arrhenius (1903), Watson.
- The primitive atmosphere was formed with gases emitted by volcanoes and trapped by gravity. Steam from volcanoes condensed due to lower temperatures. Meteorites also brought water.
- The crust formed, becoming cooler.
- Primitive soup: formed by organic compounds dissolved in water (primitive seas) as a result of chemical reactions between inorganic gases in the atmosphere.
The Origin of Cells
Lipids floating on the surface could have trapped organic compounds (maybe nucleic acids?). First RNA (transmits information and can replicate), then DNA (stable and protected). Autotrophic microorganisms (CO2, SO2 → Glucids). Cyanobacteria can use light and H2O to produce O2, enriching the atmosphere with oxygen (stromatolites in Australia 3500 million years ago). Oxygen is lethal and forced anaerobic microorganisms to live in deep ocean areas. Through evolution, heterotrophs appeared from autotrophs. Prokaryotic cells and eukaryotic cells (endosymbiosis theory by Lynn Margulis). Biotic evolution.