Upper Paleolithic nonfigurative cave paintings older figurative art

Simple cave marks are older than pictures of animals and people

Some of the oldest known cave art consists of hand shapes, lines, and geometric marks rather than pictures of animals or people. Figurative cave art appeared later, though known examples still date back at least 40,000 years.

Immune cells can attack when a normal ID badge disappears

Healthy cells normally show MHC I molecules on their surface. These act like ID badges that tell natural killer cells not to attack. Some infected or cancerous cells lose these badges, and natural killer cells can attack because the familiar signal is missing.

Poor nutrition early in life can cause lasting damage

Poor nutrition during a child's first 1,000 days can permanently limit physical and mental development. Food alone is not the whole problem: infections and parasites caused by poor sanitation can also stop the body from absorbing enough nutrients.

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Upper Paleolithic nonfigurative cave paintings older figurative art

Simple cave marks are older than pictures of animals and people

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