Analysis of the stone artifacts from zhoukoudian indicate that the tools from:
the later stages are heavier and larger than the previous stage.
all stages are identical to each other.
the earliest stages are made from flint and fine-grained quartz.
the later stages are small and the tool materials are of better quality than the previous stages.
the later stages are large and crudely made.

the later stages are small and the tool materials are of better quality than the previous stages.

Explanation:

The stone scrapers and the choppers found at the site of Zhoukoudian points out the fact that Peking men devised several tools for various purposes and to accomplish different tasks. The stones and the bones used to make the tools used to be charred by using the fire. This also indicates that the Peking men had discovered the uses of fire and they used fire for various activities.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link:

ans.

dna fingerprinting is defined as a process that determines the dna characteristics of an individual. these dna characteristics are unique among individuals as their fingerprints, so it is known as dna fingerprinting.

steps of dna fingerprinting includes extraction of dna from sample, amplification of dna, restriction digestion of amplified dna, and then analysis of dna by gel electrophoresis, respectively.

thus, the next step performed by the scientist is 'to cut the amplified dna (obtained by polymerase chain reaction) by restriction enzymes that cleave the dna into fragments and their analysis.'