Evolution works by

tinkering with existing structures

Hox genes are thought to play an important role in the development of different morphologies because they

provide positional information in the embryo.

The atmosphere of early Earth probably contained no O2 until the emergence of organisms that used

water as an electron source for photosynthesis

Radiometric dating allows us to

indirectly date fossils up to billions of years old based or minerals in surrounding volcanic strata.

The oldest fossils usually are found in

the deepest strata

Earth probably formed __________ and the first life evolved as early as _________

4.5 billion, 3.9 billion

RNA is believed to be the genetic material because RNA has both

informational storage and catalytic properties

Miller and Ureys experiments that attempted to recreate conditions on early Earth were significant because they showed that

Organic molecules such as amino acids could be produced from inorganic molecules