There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
Answer:
{Dear:friends name}
I'm writing this letter to tell you congrats on getting admitted into your dreams school!!
I know how nervous you were when the letter came.
i'm going to miss seing you around but i know that you are going to have so much fun when school starts up again .
<span>B. The have been Earth's only hominine for the last 24,000 years.
After the unknown eradication of the Homo Neanderthals, Homo Sapiens became the only homonine for the last 24,000 years. That is to say, that modern humans are the result of the evolution of homo sapiens to homo sapiens sapiens.</span>
Answer:
Incorrect
Explanation:
In the bone modelling process, osteoblasts a responsible for bone formation and osteoclasts are responsible for bone resorption. In the young adult during growth, the formation of bone exceeds the resorption of bone to maintain bone mass. Therefore,
As we get older, bone formation decreases due to reduction in osteoblastic activity and numbers and bone resorption increases as a result of sex hormone deprivation, this will result in decreased bone mass (osteoporosis). Therefore, osteoclastic activity would have to exceed osteoblastic activity in order or osteoporosis to develop
They both envole the earth
