You are at a conference for a fellow scientist who is giving a lecture in a field you
are both researching: human evolution and ancestry. In his lecture, he compares
many of the behaviors of humans and Chimpanzees, and compares the
behaviors of humans and Orangutans. He concludes that we are more closely
related to Orangutans than Chimpanzees. Is he correct?

This is an incorrect statement as orangutans are the most distant relatives of humans among the Great apes and chimpanzees are the closest.

What is the evolutionary relationship?

The link drawn between different species of organisms considering their evolutionary history is the evolutionary relationship between these species. Genome sequencing is a method to study evolutionary relationship between the organisms of different species.

The humans, orangutans, gorillas and chimpanzees are grouped together in a family called as as the Hominidae. The Genome sequencing of humans, chimpanzees and orangutans revealed that humans and orangutans share about 97% of their DNA. This is much less than humans and chimpanzees which share 99% of their DNA.

Therefore, the statement that humans are more closely related to orangutans than chimpanzees is an incorrect statement.