Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Fact 1: treating water is used to remove harmful substances before drinking. 
Fact 2: Chlorine is also used to treat water.
Chlorine is also used to remove harmful substances from water before drinking.

Fact 1: a laser is used for producing light. 
Fact 2: Lasers, for instance, produce coherent light.
Lasers are used to produce a beam that is coherent.

Fact 1: Phylogeny is the evolutionary history of a group of related organisms. 
Fact 2: Fossil evidence of human evolutionary history is fragmentary and open to various interpretations.

In phylogeny, you may look into fossils in order to gain better understanding of how an organism came to be.