A once-maligned genetic parasite may actually be essential for survival.

Mouse embryos need that genetic freeloader — a type of jumping gene causing mutations, or transposon, called LINE-1 — to continue developing past the two-cell stage, researchers reported in Cell.

Transposons certainly can hop into and break genes, and cells deploy numerous tools to prevent the jumping genes from making RNA and protein copies of themselves. But, in early development, LINE-1 is turned on nearly full blast, packing RNA into embryonic cells as well as “germline” cells, which later give rise to eggs and sperm.

To see what the jumping gene was doing in the cells, scientists used a short piece of RNA that could pair up with LINE-1 RNA and cause the transposon to be degraded, essentially turning off the jumping gene. (The researchers couldn’t simply remove LINE-1 from a cell; there are thousands of copies) Without LINE-1 RNA, embryonic stem cells stopped making more of themselves and mouse embryos failed to progress past the two-cell stage of development. (1)

Meet life.

In death.

Look into the ground you step upon.

For mother Earth, life and death were never important.

Live. Die. Be.

This is the essence of life.