What Does Genesis 30:40 Mean?

Jacob separated the lambs and set the faces of the flocks toward the striped and all the black in the flock of Laban. He put his own droves apart and did not put them with Laban's flock. The second element of Jacob's breeding strategy: he separated the animals selectively. He positioned the normal-colored females to face the striped and black males while mating, again using visual stimuli theory. More importantly, he kept his own growing herd separate from Laban's, preventing the genetic mixing that would reduce the proportion of abnormally colored offspring in his group.

The separation of Jacob's own "droves" (agudah, a group of animals driven together) from Laban's flock is essential for the strategy to work over time. If Jacob's abnormal-colored animals were mixed back into Laban's normal-colored majority, the selective breeding advantage would be diluted. By maintaining two separate herds, Jacob ensured that his animals bred primarily with each other, concentrating the traits that would continue producing abnormally colored offspring.

The animal breeding strategy described in verses 37-43 reveals that Jacob had been observing the genetics of the flock throughout his twenty years with Laban, understanding which parent pairs produced which offspring types. The six years of the wage arrangement allowed him to apply this observed knowledge in self-interested ways for the first time. Laban's flocks provided the education; Jacob's final contract provided the opportunity to use it.