OHS2020 Chap3
Why are we only looking for fossiles in Africa and no elsewhere?
It's not true. There is other sites (look at the map at p.95 or 114).--AlinaM (discussion) 31 mars 2020 à 19:11 (CEST)
How does palaeomagnetism work ? (p.37)
Palaeomagnetism is a method which consists in estimating the age of fossils by analyzing and observing the alignment of particles in the deposit surrounding a particular fossil. This is possible because the Earth's magnetic field undergoes sequences of changes at different timings which allows magnetically charged particles to align themselves in function of the magnetic pole and to keep their orientation when they are consolidated into rock with fossils. That way by analyzing the position and orientation of different particles surrounding a fossil its age can be determined. --VictoriaW (discussion) 2 avril 2020 à 20:20 (CEST)
What are radiometric techniques used for ? (p.48)
Radiometric techniques are used to determine the age of volcanic deposits. By doing that, one can determine the age of the fossils that are found between the layers of ash. --IlliaB (discussion) 3 avril 2020 à 09:43 (CEST)
With what is sexual dimorphism linked to ? (p.61)
In primates, sexual dismorphism is expressed as "a ratio of average male body-weight to average female body-weight." By Humans, Bonobos and Chimpanzees the sexual dismorphism is pretty low in contrast with Gorillas for example who express a high sexual dismorphism. The cause of high sexual dismorphism is the social system in which male primates are in a competitive environnement with other males.--NoraM (discussion) 5 avril 2020 à 11:51 (CEST)
How did we discover tool-makers ? (p.68)
The first traces of tools date back more than 3.3 million years. They were discovered at the Kenyan site of Lomewki. We know that they are tools because we notice that the stones have been cut, and on the site, we find marks of cuts made by these tools on various fossilized bones.
Traces of butchering tools dating back 2.5 million years have also been found. Cuts and tears were found on the remains of the carcasses. arno
What are the key adaptations of the humans hand to have great tool-making abilities ? (p.69)
To be able to create tools, three capabilities are required: precision handling, precision grip and power grip. The thumb and fingertips are more useful for the precision capabilities. Precision handling is for rotating and manipulating objects with one hand thanks to the fingertips and the thumb and precision grip is for pressing the thumb and fingertips together with enough strength and the last one is more for force. Power squeeze uses the finger , the thumb and the palm of the hand in order to stabilize the object. --ThomasG (discussion) 6 avril 2020 à 15:26 (CEST)
What shows anatomical diversity ?
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