In a documentary I saw that after 30,000 years only our bones remain. How is that possible since we have already found fossils from 500 million years ago?
Answer
Dear Nelson,
What an interesting question. How is this possible? That is fairly easy to answer.
Everything has to do with the way in which e.g. human remains (but also remains of animals or plants) are preserved.
When a human body ends up in the ground, it doesn’t take long before only a skeleton remains, but a skeleton generally doesn’t survive very long in the soil either. As archaeologists, we regularly find skeletons from the Middle Ages (about 500 to 1000 years ago). From Roman times (about 2000 years ago) this is already much more difficult because many skeletons have already been ‘dissolved’ by the soil.
Only in special circumstances are bodies or skeletons preserved for a longer period of time. Just think eg. to bog bodies. These people ended up in a swamp after their death and due to the lack of oxygen under water, eg. many bacteria do not ‘eat’ the body, so that it lasts longer. Another good example are, for example, the bodies of prehistoric elephants or mammoths that were ‘frozen’ in the ice caps of eg. Russia. Because they were kept frozen there for thousands of years, scientists can now examine them in great detail. Also mummies that are often thousands of years old
Something similar happens with fossils. A fossil is created when the body of a shell, plant, animal, … is able to transform itself into a kind of ‘stone’ through various processes. So a fossil is actually a petrified animal or plant. Because it acquires the properties of stone, it can survive much longer just like stone and we also know animal species that are many millions of years old.
How long something is preserved can therefore vary greatly.
Exciting right?
Tim Clerbaut
Answered by
PhD student Tim Clerbaut
archeology archaeology
http://www.ugent.be
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