“To death or time it stopped growing. Radiometric
“To give meaning to where we are today, we need to look at where we’ve have come from. ” -Richard Leakey, in National Geographic, February 1998 After millions of years of evolution, primate has finally become man. The people responsible for all the discoveries of the past we now know are the scientist we know today to be the paleo-anthropologists of the past and present. Paleo-anthropologist have conceived a world unknown to use only a century ago by using the methods comparable to those of most other scientist.
It wasn’t even until the 1900’s began that scientist were able to grow in paleo anthropology because of the great advancements made in testing the evidence in several different ways. Many of these test included dating techniques. Radiocarbon1 dating is currently the most precise and reliable dating method used today. It was invented in 1949 by J. R. Arnold and W. F. Libby2 and didn’t take long before it took to science and studies of early man. Many scientists could use this method on nearly any non-living organism to test for time of death.
This method is used to find the radioactivity and the rate of decay of an atom, which can therefore lead to finding the time of death or time it stopped growing. Radiometric dating is almost similar to radiocarbon dating in that it uses half-life and carbon atoms to find the needed information to date the material. Although this is the most commonly used method it has it limitations. To date a material it requires a sufficient amount to properly date it. These procedures can be helpful in dating objects not only located on the organism but around it as well.
For example, a paleo-anthropologist can find a skeletal remain and may only need to take a sample of the sediment or rock it was found in and aid, maybe even pin-point, the time that skeleton was put there. One on the reliable method could be said to be dendrochronology2, or also known as tree ring counting. This technique is simple in that it needs little information to date something. As a tree grows it slowly is growing layer, around layer, around another and as this process continues it created rings that when you know the rate of growth you can determine by counting the rings, how old it is.
Although it’s accurate factors like weather can slow down the rate that the rings grow therefore lowering the accuracy. These factors can however be taken into account or worked around. Another form of dating is cross-dating. Cross-dating is a familiar dating method to most in that it include artifacts or bone in the side of a mountain or in stone as is seen on television when associated with archeologists, but paleo-anthropologist use this approach as well. This is simple process which is shown in the following figure.
Where the lines connect to another block of a similar shade, it is relating to the rock types that may have been found, after millions of years of movement and shifting, side by side. With this information they can estimate what time the artifact that was found belonged in or they can carbon-date rock material surrounding it. A widely known paleo-anthropologist is Louis Leakey as well as his wife Mary Leakey and even their son Richard Leakey. All accomplished wonders in their life. Louis and Mary discovered a new species of early man that is now called Australopithecus boisei in 1959 in one of the oldest digging sites ever3.
This made the Leakey’s famous for the fact that it was estimated at 1. 75 million years. Mary Leakey, on the other hand, is greatly known for finding footprints that opened the door to much more evidence to support Donald Johanson’s earlier findings of the skeletal remains of a 3. 2 million year old woman who as named Lucy4 who was discovered in Hadar, Ethiopia5. To find this evolution changing evidence it simply took looking for them to find them. Of course you must look in the right places, which could be a deep valley that was millions of years ago inhabited and was moderately kept out of others hands.