The inhabited history of the Las Vegas Valley stretches to 23,000 b.c. , when much of the area was covered by a prehistoric lake. During this period, the indigenous people lived in caves, hunting the mammals that gathered at the shoreline. The landscape of the valley changed dramatically over the next 200 centuries. The glaciers feeding the lake melted away and the lake evaporated. Fossils tell an obscure story of man's slow and sporadic development. Around 3000 b.c. , native Archaic Indians began to develop a lasting hunting and gathering culture. By this time, the valley was in much the same geographic state as it exists in today, with one exceptionthe presence of artesian springs that bubbled to the surface in several areas. These springs fed a network of streams draining through the Las Vegas Wash to the Colorado River. The areas surrounding the springs were desert oases: sprawling collections of grasses, trees, and wildlife. Many springs lay in areas that would eventually become the center of the modern Las Vegas metropolis. For about 4000 years, the Archaics thrived in a culture that included many signs of early civilization. Signs of even more advancement appeared halfway through the first millennium a.d. , when the Anasazi Indians inhabited the valley. Far more progressive than the Archaics, the Anasazi utilized such formal agricultural techniques as irrigation to assist their harvest. This permitted the Anasazi to achieve a benchmark of advanced societythe ability to live in permanent shelters year-round without need to follow wildlife. Mysteriously, the Anasazi vanished from the valley around a.d.

Question: "When does Las Vegas history begin and what covered most of the area?"

Answer: "Around 3000 b.c., Colorado River"

Response: no

(CNN) -- Beyond skateboards, Silicon Valley and hippies, California has a trendsetting streak of a different kind. The state has been first to pass major public health initiatives that have spread throughout the country. California was first to require smog checks for clean air, pass anti-tobacco initiatives and bike helmets laws. While these laws were met with skepticism and ridicule, they've often become standard practice in other states. The Golden State was first to ban smoking in workplaces, bars and restaurants in 1998. Now similar rules exist throughout the country. Some advocates tout the state as a forward-thinking vanguard in which its health and safety laws are routinely emulated by other states. "There have been progressive legislations in tobacco, environment and obesity prevention," said Mark Horton, a lecturer at the University of California Berkeley School of Public Health. "In some respect, the rest of the country looks to California as a laboratory for moving forward with those various types of initiatives." But some critics liken the Golden State to a nanny state. California has 151,002 health and safety laws. "It never ends," said Laer Pearce, who works in public affairs in Orange County. "Every year, several hundred bills come through and dozens of them tell us how to live our lives." Starting in January, 760 new California laws went into effect -- for example, the importing of shark fins is prohibited, student athletes are required to have medical clearance after suffering a head injury, teens are banned from using tanning booths and the sale of caffeinated beer is forbidden. There's a perception that California has "more folks who are health-oriented and more health-minded," said Horton, former director of the California Department of Public Health. It's not just workout fanatics hanging out at Muscle Beach, Sierra Club members hiking mountains or the uber-health-conscious touting organic foods. Californians in general tend to have healthier habits, ranking 10th for physical activity, fourth for healthy blood pressure and fifth for a diet high in fruits and vegetables compared with other states, according to America's Health Rankings.

Question: "What state became the first to pass major public health initiatives?"

Answer: "Minnesota"

Response: no

Breathing is the process of moving air into and out of the lungs. The process depends on a muscle called the diaphragm. This is a large, sheet-like muscle below the lungs. Inhaling, or breathing in, occurs when the diaphragm muscle tightens. This increases the size of the chest. This too decreases air pressure inside the lungs. This action allows air and gases to enter the lungs. Exhaling, or breathing out, occurs when the diaphragm muscle relaxes. This decreases the size of the chest. This increases air pressure inside the lungs. This action allows for air to leave the lungs. When you inhale, air enters the respiratory system through your nose and ends up in your lungs, where gas exchange with the blood takes place. What happens to the air along the way? In the nose, mucus and hairs trap any dust or other particles in the air. The air is also warmed and moistened. Next, air passes through a passageway that is connected to the windpipe. The air then finds its way to the lungs. In the chest, the windpipe splits so that air enters both the right and left lung.

Question: "When you exhale, why does air leave your lungs?"

Answer: "Due to decrease in air pressure"

Response: no

Fossils may form in other ways. Fossils can be preserved almost completely. In this process, the organism doesnt change much. As seen below, tree sap may cover an organism. With time, the sap hardens. It turns to into amber. The original organism is preserved. This is very exciting for scientists. They are able to study the DNA of the organism that no longer lives on Earth. Some animals have been found frozen in ice. Others have been found in tar pits after falling in. Molds and casts are another way organisms can be fossilized. Have you ever walked in soft mud and left footprints? Once in a while, these traces of organisms can be preserved. In this case, nothing is left of the organism. A mold is an imprint of an organism that is preserved in rock. The organisms remains break down completely. There is nothing left of the original plant and animal.

Question: "What can scientists study about a fossil found in amber, that they normally cannot with most fossils?"

Answer: "DNA"

Response:
yes