Fossils hint ancient humans passed through a green Arabia | Science News for Students

Fossils hint ancient humans passed through a green Arabia

Ancient animal bones and stone tools from the now-harsh region date back 300,000 years
Nov 20, 2018 — 6:45 am EST
antelope fossil

Researchers at a site in Saudi Arabia dug up ancient stone tools and animal fossils, including these teeth and jaw bones from an antelope.

PALEODESERTS PROJECT, IAN R. CARTWRIGHT

The Arabian Peninsula is the part of southwestern Asia that includes Saudi Arabia and other countries. Today this region is known for its harsh deserts. But at least 300,000 years ago, it was a green hot spot for migrating members of the human genus. That’s the finding of a new study.

Patrick Roberts and his colleagues studied an ancient site called Ti’s al Ghadah. Roberts is an archaeologist at the Max Planck Institute for the Science of Human History in Jena, Germany. This Saudi Arabian site held fossils of antelopes, elephants and other animals. Among those fossils were stone tools made by long-ago humans or their relatives. Those tools are between 300,000 and 500,000 years old.

Two animal fossils at Ti’s al Ghadah seemed to have butchery marks on the bones. In other words, someone cut up the carcasses to eat them. That would mean hunting happened at this site, the researchers now conclude.

The researchers looked at 21 animal teeth from the site. They were looking for chemicals that would indicate what the animals had eaten. Those chemicals suggest that the ancient environment looked like today’s grassy savannas in East Africa. Forms of carbon in the animals’ teeth reflected a grassy menu. And forms of oxygen showed that the animals regularly drank water from ponds or other sources fed by rainfall.

These data point to that long ago site as being a grassy, green region regularly fed by rain. The researchers described their findings online October 29 in Nature Ecology & Evolution.

Homo sapiens, our species, arose in Africa roughly 300,000 years ago. Later, members of our species left Africa and spread across the world. Scientists have estimated that those migrations began about 60,000 years ago. But recent finds on the Arabian Peninsula had suggested that those migrations began much earlier. For example, researchers found a human finger fossil from at least 86,000 years ago.

Some ancient toolmakers passed through Ti’s al Ghadah a few hundred thousand years ago. They may have been Homo sapiens. Or they may have been another Homo species that journeyed out of Africa, say Roberts and his team. Whoever they were, these groups found a friendly, green climate waiting for them.

Power Words

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carbon     The chemical element having the atomic number 6. It is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

climate     The weather conditions that typically exist in one area, in general, or over a long period.

colleague     Someone who works with another; a co-worker or team member.

ecology      A branch of biology that deals with the relations of organisms to one another and to their physical surroundings. A scientist who works in this field is called an ecologist.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of things in the vicinity of an item of interest).

evolution     (v. to evolve) A process by which species undergo changes over time, usually through genetic variation and natural selection. These changes usually result in a new type of organism better suited for its environment than the earlier type. The newer type is not necessarily more “advanced,” just better adapted to the particular conditions in which it developed. Or the term can refer to changes that occur as some natural progression within the non-living world (such as computer chips evolving to smaller devices which operate at an ever faster speed).

fossil     Any preserved remains or traces of ancient life. There are many different types of fossils: The bones and other body parts of dinosaurs are called “body fossils.” Things like footprints are called “trace fossils.” Even specimens of dinosaur poop are fossils. The process of forming fossils is called fossilization.

genus     (plural: genera) A group of closely related species. For example, the genus Canis — which is Latin for “dog” — includes all domestic breeds of dog and their closest wild relatives, including wolves, coyotes, jackals and dingoes.

Homo     A genus of species that includes modern humans (Homo sapiens). All had large brains and used tools. This genus is believed to have first evolved in Africa and over time evolved and radiated throughout the rest of the world.

migration     (v. migrate) Movement from one region or habitat to another, especially regularly (and according to the seasons) or to cope with some driving force (such as climate or war). An individual that makes this move is known as a migrant.

oxygen     A gas that makes up about 21 percent of Earth's atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).

peninsula     A parcel of land that is that is attached to the mainland but surrounded by water on three sides.

savanna     A grassland sometimes also populated with trees. Most are fairly dry for part or much of the year.

species     A group of similar organisms capable of producing offspring that can survive and reproduce.

Citation

Journal: P. Roberts et al. Fossil herbivore stable isotopes reveal middle Pleistocene hominin palaeoenvironment in ‘Green Arabia.’ Nature Ecology & Evolution. Published online October 29, 2018. doi: 10.1038/s41559-018-0698-9.