<span>Because the atmosphere is thinner, there would be less pressure keeping the heart at its current size and it would expand and become too large to work properly</span>
Ribose sugars
Cytosine
Thymine
Transfer RNA
Uracil
Ribosomal RNA
Nucleotides
Messenger RNA
By studying fossils, scientists can learn how much (or how little) organisms have changed as life developed on Earth. There are gaps in the fossil record because many early forms of life were soft-bodied, which means that they have left few traces behind. This is why scientists cannot be certain about how life began.
