Air Date: Week of December 10, 2004

Living on Earth’s Jennifer Chu reports on findings that the human parathyroid gland may have fishy evolutionary roots.

Transcript

CURWOOD: Just ahead: up close and personal with everyone’s mother, Earth. First, this Note on Emerging Science from Jennifer Chu.

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CHU: It may sound fishy, but scientists think vestiges of our days swimming in the earth’s primordial seas may linger in us to this day. Scientists at King’s College in London say the human parathyroid gland, which regulates calcium levels in the body, may be a throwback to the gills of fish that eventually evolved into the first land-living animals.

Like the parathyroid gland, the gills of fish—both modern and prehistoric—regulate calcium, which is essential to the body’s ability to move muscles and trigger nerve cells. Both gills and parathyroid glands are located in the neck and both develop from the same type of embryonic tissue. What’s more, humans and fish share a similar gene that’s needed for the parathyroid glands and gills to develop correctly.

As an organ of the endocrine system, the gland could have developed anywhere in the body. But researchers say their findings help answer the question of why the parathyroid gland is located in the necks of humans and other land animals. The findings appear in the current edition of the Proceedings of the National Academy of Sciences. That’s this week’s Note on Emerging Science, I’m Jennifer Chu.

CURWOOD: And you’re listening to Living on Earth.

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[MUSIC: Tony Rice “Gold Rush” THE BLUEGRASS GUITAR COLLECTION (Rounder – 2003)]