The Phoenix area had no sizable Mexican presence before the U.S. took over the territory. Some assumed that the region was founded completely by whites from the outset. Whites and Mexicans actually held nearly equal populations throughout the first two decades of settlement. Though they did not hold equal status,…
The Phoenix area had no sizable Mexican presence before the U.S. took over the territory. Some assumed that the region was founded completely by whites from the outset. Whites and Mexicans actually held nearly equal populations throughout the first two decades of settlement. Though they did not hold equal status, their cohabitation was largely characterized by mutual interdependence and respect. Transforming the Salt River Valley's desert terrain into a regional agricultural hub depended on the Sonorans' preindustrial skills. As the town modernized, a new class of resident sought large scale projects to integrate Phoenix into the U.S. economy. Two pivotal projects achieved this. First, railroad spur lines made Phoenix accessible for migrants, as well as allowing farmers to supply commercial markets profitably. Second, the massive Roosevelt Dam secured a stable water supply for valley farmers. While these projects provided the foundation for development, it was cotton that brought commercial success. Throughout World War I, valley cotton growers capitalized on the booming cotton market by expanding their average acreage from 400 acres in 1912 to 130,000 acres in 1920. This rapid escalation to meet wartime demands depended upon a massive seasonal labor force from Mexico. While this boom brought prosperity to valley farmers, it solidified the Mexican's role in the Salt River Valley as little more than a laborer. Valley cotton growers impressively managed all labor issues through a well-organized collective association. Over-recruitment and wage setting kept workers from collective bargaining for better wages. The cotton growers' hegemony crashed along with cotton prices in 1921. Though the industry recovered fairly quickly, the cotton growers faced a new challenge in the rising national clamor to restrict Mexican immigration to the U.S. Though growers fought restrictions in Congressional hearings throughout the decade, the economic crash of 1929 finally ended widespread Mexican immigration. By the time of the crash, most Mexicans who remained lived in the agricultural peripheries or scattered urban barrios.
Leonard Hayflick studied the processes by which cells age during the twentieth and twenty-first centuries in the United States. In 1961 at the Wistar Institute in the US, Hayflick researched a phenomenon later called the Hayflick Limit, or the claim that normal human cells can only divide forty to sixty…
Leonard Hayflick studied the processes by which cells age during the twentieth and twenty-first centuries in the United States. In 1961 at the Wistar Institute in the US, Hayflick researched a phenomenon later called the Hayflick Limit, or the claim that normal human cells can only divide forty to sixty times before they cannot divide any further. Researchers later found that the cause of the Hayflick Limit is the shortening of telomeres, or portions of DNA at the ends of chromosomes that slowly degrade as cells replicate. Hayflick used his research on normal embryonic cells to develop a vaccine for polio, and from HayflickÕs published directions, scientists developed vaccines for rubella, rabies, adenovirus, measles, chickenpox and shingles.
Although best known for his work with the fruit fly, for which he earned a Nobel Prize and the title "The Father of Genetics," Thomas Hunt Morgan's contributions to biology reach far beyond genetics. His research explored questions in embryology, regeneration, evolution, and heredity, using a variety of approaches.
