by Rabbi Yair Hoffman

An article in Nature Communications by an NYU team may teach a new pshat in a pasuk in Sefer Yirmiyahu.  In Yirmiyahu 17:10 the pasuk states:

“I, Hashem, search the heart and examine the kidneys (bochen klayos), to give to each person according to his ways, according to the fruit of his deeds.”

A Remarkable Scientific Validation

The phrase “bochen klayos” (בֹּחֵ֣ן כְּלָי֔וֹת) – literally “examine the kidneys” – has long puzzled meforshim. -and most interpreted it metaphorically.

I would like to perhaps give a more literal interpretation based upon new groundbreaking research from New York University which perhaps has revealed an astounding scientific basis for this precise terminology.

Scientists have discovered that kidney cells, like brain neurons, possess the ability to learn and form memories. “Learning and memory are generally associated with brains and brain cells alone, but our study shows that other cells in the body can learn and form memories, too,” explains New York University’s Nikolay V. Kukushkin, the lead author of the study, which appears in the latest edition of the  journal Nature Communications. This finding provides a new perspective on perhaps why the pasuk specifically mentions testing the kidneys alongside searching the heart.

The Science of Kidney Memory

The NYU study demonstrated that kidney tissue cells can:

• Recognize patterns in chemical signals
• Form “memories” of these patterns
• Respond differently to spaced versus concentrated exposures
• Activate the same “memory gene” that brain cells use

When the researchers exposed kidney cells to patterned chemical signals, these cells demonstrated learning abilities previously thought to exist only in neural tissue. They activated a specific memory gene and retained information about the patterns they experienced.

Understanding “Bochen Klayos”

The phrase “bochen klayos” now takes on remarkable new meaning. When the pasuk speaks of Hashem “testing the kidneys,” it may be referring to a profound biological reality: our kidneys actually do store memories at a cellular level.

The pairing of heart and kidneys in the pasuk may suggest a comprehensive examination of both conscious thought (heart) and unconscious cellular memory (kidneys). This dual testing provides insight into both what we consciously choose and what our bodies have learned and remembered at a cellular level.

The Tree Metaphor Revisited

The pasuk two psukim earlier with the moshol of the tree by water gains additional significance in light of this research. Just as kidney cells demonstrate memory capabilities, the tree’s cells – including its roots seeking water – possess similar learning abilities. The tree’s successful adaptation to its environment depends not just on its location but on cellular memories throughout its structure.

The specificity of “bochen klayos”  refers to a specific site of meaningful information about a person’s patterns of behavior and response. Perhaps the use of “kidneys” in this pasuk was neither arbitrary nor poetic, but reflects an insight into human biology that science is only now beginning to understand.

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