Explain how isotopes and other biomarker molecules carry information about the history of life, giving two specific examples.

Isotopes and biomarker molecules carry information about the history of life by providing clues about the environment, diet, and evolutionary relationships of organisms. Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons, leading to differences in atomic mass. These isotopes can be used to track the movement of organisms, the climate they lived in, and the sources of their food. For example, the ratio of carbon isotopes in fossilized plants can reveal information about the levels of atmospheric carbon dioxide during different time periods, providing insight into past climate conditions. Additionally, the analysis of oxygen isotopes in the shells of marine organisms can help reconstruct ancient ocean temperatures and the composition of seawater.

Biomarker molecules, such as lipids, proteins, and DNA, can also provide valuable information about the history of life. For instance, the presence of specific biomarkers in ancient sediments can indicate the types of organisms that lived in a particular environment and their evolutionary relationships. One specific example is the use of biomarker molecules to study the origins and evolution of early life on Earth. By analyzing the distribution of certain biomarkers in ancient rocks, scientists have been able to infer the presence of microbial communities and the types of metabolism that were prevalent billions of years ago. Another example is the analysis of ancient DNA from fossilized remains, which has provided insights into the genetic relationships between extinct species and their modern descendants, shedding light on the evolutionary history of life on Earth. Overall, isotopes and biomarker molecules are powerful tools for reconstructing the history of life and understanding the processes that have shaped the diversity of organisms on our planet.