Radiocarbon dating before present
allometry: The relation between the size of an organism and the size of any of its parts.For example, an allometric relation exists between brain size and body size, such that (in this case) animals with bigger bodies tend to have bigger brains.These all develop through an embryo that is enclosed within a membrane called an amnion.The amnion surrounds the embryo with a watery substance, and is probably an adaptation for breeding on land.amphibians: The class of vertebrates that contains the frogs, toads, newts, and salamanders.The amphibians evolved in the Devonian period (about 370 million years ago) as the first vertebrates to occupy the land.antibacterial: Having the ability to kill bacteria.antibiotics: Substances that destroy or inhibit the growth of microorganisms, particularly disease-causing bacteria.
algae: An umbrella term for various simple organisms that contain chlorophyll (and can therefore carry out photosynthesis) and live in aquatic habitats and in moist situations on land. Algae range from macroscopic seaweeds such as giant kelp, which frequently exceeds 30 m in length, to microscopic filamentous and single-celled forms such as Spirogyra and Chlorella. For example, if a gene determines the seed color of peas, one allele of that gene may produce green seeds and another allele produce yellow seeds.
artifact: An object made by humans that has been preserved and can be studied to learn about a particular time period.
artificial selection: The process by which humans breed animals and cultivate crops to ensure that future generations have specific desirable characteristics.
The diameter of the aperture determines the intensity of light admitted. archeology: The study of human history and prehistory through the excavation of sites and the analysis of physical remains, such as graves, tools, pottery, and other artifacts.
The pupil of a human eye is a self-adjusting aperture. archetype: The original form or body plan from which a group of organisms develops.
Peaks on the landscape correspond to genotypic frequencies at which the average fitness is high, valleys to genotypic frequencies at which the average fitness is low. adaptive logic: A behavior has adaptive logic if it tends to increase the number of offspring that an individual contributes to the next and following generations.