The term includes all of human existence prior to the emergence of writing

Milk production during breastfeeding is increased by the suckling of a newborn from his mother's nipple. this type of feedback mechanism best describes a positive or negative

The ruiz family is exchanging euros for us dollars. the exchange rate is 1 euro equals 1.35261 usd. since the ruiz family knows that usd are stated to the nearest hundredth of a dollar, they used the conversion ratio

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes