Science Proves Weird Bible Story True
September 14, 2020 Blogs by: Tim Jennings, M.D.

Have you ever read the story of Jacob stripping bark off tree limbs in order to get his sheep to give birth to streaked, speckled, or spotted offspring? You can find it in Genesis chapter 30.

Having completed his fourteen years of labor, as payment to Laban for his wives Leah and Rachel, Jacob was planning on returning home to his father Isaac. But Laban wanted him to stay, so the two negotiated a payment arrangement for Jacob: All the new lambs born that were solid colored would be Laban’s, but any born that were streaked, speckled, or spotted would be Jacob’s.

As soon as the agreement was reached, however, Laban sought to undercut Jacob’s earning by removing all the streaked, speckled, and spotted sheep from the flocks. The very day the agreement was made, Laban had his sons take away any sheep that did not have solid fur far so that they wouldn’t breed with the solid-colored sheep.

In response, we have the strange account of Jacob peeling the bark off tree branches and placing the branches in the sheep’s drinking water in order to breed more lambs that were streaked, speckled, or spotted.

Jacob, however, took fresh-cut branches from poplar, almond and plane trees and made white stripes on them by peeling the bark and exposing the white inner wood of the branches. Then he placed the peeled branches in all the watering troughs, so that they would be directly in front of the flocks when they came to drink. When the flocks were in heat and came to drink, they mated in front of the branches. And they bore young that were streaked or speckled or spotted (Genesis 30:37–39 NIV84).

This story has generated a wide range of responses. Critics have used it to mock the Bible. Others try to explain it as Jacob being superstitious. But science has now documented this story is simply the outworking of the laws of biology – how God created reality to work.

agouti gene.jpgThere is a gene – the agouti gene – that determines the color an animal’s fur. If all the agouti genes in the cells are turned either on or off, the animal will be solid-colored. But if this gene is turned on in some cells and off in others, the animal will be speckled, streaked, or spotted. In this image there are five cloned mice (genetically identical), yet their fur looks different. The mouse on the far left has all of its agouti genes turned on and, thus, is solid yellow. The mouse on the far right has all its agouti genes turned off and is solid brown. But the three mice in the middle have some of the agouti genes turned on and some turned off, and their fur is streaked, speckled, or spotted.

But what turns the agouti gene on or off? The diet of the mother when she is pregnant! If the diet has certain nutrients, the gene is turned either on or off, thus changing the expression and the fur of the animal.[1] And this change will pass down up to four generations, thereby increasing the number of speckled, spotted, or streaked offspring.

But is this true only in mice? No! Recent research has documented that the branches of the trees chosen by Jacob do, in fact, provide the nutrients needed to alter the expression of the agouti gene, which does, in turn, alter the color of the lambs born.[2]

Jacob’s actions were not superstition, but rational, scientific, and consistent with how God created reality to operate. The Bible is again proven to be true!

That’s why when you read stories in the Bible that seem strange or weird, don’t doubt the Bible; instead, search for the evidence, truth, facts, and insights and come to a reality-based understanding of the true meaning of what is written and described.

Rightly understood, the Bible and science always agree – for our God is the Author of both!


[1] Dolinoy, D., The agouti mouse model: an epigenetic biosensor for nutritional and environmental alterations on the fetal epigenome. Nutr Rev. 2008 Aug; 66(Suppl 1): S7–11.

[2] Backon, Joshua, Jacob and the Spotted Sheep: The Role of Prenatal Nutrition on Epigenetics of Fur Color. Biology, 2008. https://www.semanticscholar.org/paper/Jacob-and-the-Spotted-Sheep%3A-The-Role-of-Prenatal-Backon/194ef71dd0af81f87cebdeda41ac64a85bc44a74


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Tim Jennings, M.D. Timothy R. Jennings, M.D., is a board-certified psychiatrist, master psychopharmacologist, Distinguished Life Fellow of the American Psychiatric Association, Fellow of the Southern Psychiatric Association, and an international speaker. He served as president of the Southern and Tennessee Psychiatric Associations and is president and founder of Come and Reason Ministries. Dr. Jennings has authored many books, including The God-Shaped Brain, The God-Shaped Heart, and The Aging Brain. In 2022, Dr. Jennings became Chair of the Department of Psychiatry and Behavioral Health at Liberty University College of Osteopathic Medicine in Lynchburg, Virginia.