Human handedness is a unique trait among primates, with 70-95% of people being right-handed. The origin of handedness is tied to the development of tool use and bipedalism, which led to brain lateralization, where the left hemisphere controls the right side of the body. This is evident in the fossil record, with evidence of handedness found in 500,000-year-old teeth from Spain and 1.8 million-year-old teeth from Tanzania. While the exact mechanism is unclear, research suggests that handedness is heritable and influenced by multiple genes. Interestingly, left-handed individuals may have an evolutionary advantage in certain situations, such as physical combat, due to their less lateralized brains.
Here are the facts extracted from the text:
1. A Neanderthal individual lived about 130,000 years ago in what is now Croatia.
2. The orientation of scratches on Neanderthal teeth suggests that most Neanderthals were right-handed.
3. 70-95% of humans are right-handed.
4. No other placental mammal has a consistent preference for one side of the body.
5. No human population has been recorded as being mostly left-handed.
6. Handedness is associated with brain lateralization and tool use.
7. The left hemisphere of the brain controls the right side of the body, and vice versa.
8. 99% of people have a dominant hand.
9. Cave paintings from the Late Pleistocene depict mostly right-handed artists.
10. The bone of the dominant upper arm becomes thicker in certain places compared to the non-dominant arm.
11. Scientists have found microscopic scratches on Neanderthal teeth caused by tools.
12. Similar scratches have been found on 500,000-year-old teeth from Spain belonging to Homo heidelbergensis.
13. Scratches have also been detected on the teeth of a 1.8 million-year-old Homo habilis from Tanzania.
14. Handedness is heritable, but there is no single "handedness" gene.
15. Men are more likely to be left-handed than women.
16. Brain scans have shown that left-handed people tend to have less lateralized brains than right-handed people.
17. Left-handed people may have an advantage in physical combat due to the element of surprise.
18. Left-handed boxers and mixed martial artists win matches more often than their right-handed opponents.
19. The frequency of left-handedness is consistently low across populations.
20. Bipedalism may be associated with handedness, as seen in kangaroos.
21. The exact origin of right-hand preference is unclear.