how does the author describe humans' ability to decipher animals' facial expressions and how that might affect humans' relationships with animals?

According to the author, the humans now have the ability to read the facial expression of animals when they are in pain. For instance, it's been discovered that lambs grimace when they are in pain.

This milestone achievement, according to him will improve the welfare accorded to animals being used for scientific experiments for testing or when they are being converted to food.

Cheers!