Dating rocks and fossils using radioisotopes
The mass spectrometer is able to give information about the type and amount of isotopes found in the rock.Scientists find the ratio of parent isotope to daughter isotope.Fossils are collected along with rocks that occur from the same strata.These samples are carefully cataloged and analyzed with a mass spectrometer.D.3.1 Outline the method for dating rocks and fossils using radioisotopes, with reference to 14C and 40K.Knowledge of the degree of accuracy and the choice of isotope to use is expected.
By allowing the establishment of geological timescales, it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change.
In summary: Big brains are energetically expensive.
The mother must take in lots of energy not only during pregnancy, but for a significant time after.
You can’t really see it but the hole in the bottom of the skull where the spinal cord exits the brain (foramen magnum) is further forward in modern humans.
This distributes the weight of the head over the spine so that modern humans do not need huge necks muscles.