4 Quotes by Martin Kennedy

One of the things we least understand is why animals evolved so late in Earth history. Why did animals wait until the 11th hour, whereas evidence for more primitive life dates back billions of years? One of the best bets to explain the difference is an increase in oxygen concentration in the atmosphere.

NASA is interested in what conditions to look for on other planets that might lead to the arrival of life. What are the processes? Using earth as our most detailed study site, what are the necessary steps a planet needs to go through to enable complex animal life to arise? If oxygen is the metabolic pathway, then we need to know what conditions have to allow for that to happen. The geologic record provides us with a record of these steps that occurred on Earth.

We predicted we would only find a significant percentage of clay minerals in sediments toward the end of the Precambrian, when complex life arose, while earlier sediments would have less clay content. This test is easier than it sounds. Because clay minerals make up the bulk of sediment deposited today, we are saying that it should be largely absent in ancient rocks. And this is just what one finds.

The clay minerals are acting essentially like kitty litter, absorbing organic molecules in the oceans. This is totally, absolutely new.