Today_I_Learned

Sharks appeared long before the first modern forests and before many of the plants we know today had evolved. That means the ocean once had giant predators before the land had giant trees.

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r/Today_I_Learned_This • u/unteachablecourses • 12d ago

JFK's tan — the visual signature of his "vigor" — was partly a symptom of Addison's disease, which darkens the skin. His filled-out face was partly the cortisone keeping him alive. The cameras selling the image of health were recording the side effects of a fatal illness.

6 Upvotes

1 comment

r/Today_I_Learned_This • u/unteachablecourses • 14d ago

San Francisco's white-crowned sparrows sing in 18 distinct neighborhood dialects — Presidio, Lake Merced, Marin Headlands — some only a few hundred meters apart. Females prefer their local accent when choosing mates & a 2024 study found adjacent neighborhoods are genetically diverging as a result.

2 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • 15d ago

The 2003 Antwerp diamond vault heist is the cleanest case study in how defense-in-depth fails. Ten independent layers, each beaten by something trivial — hairspray on the IR sensor, aluminum tape on the magnetic contact — because the attacker had 2.5 years of legitimate tenant access to study them.

2 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • 22d ago

A crypto company CEO bought RealDoll in 2024, reverse-merged it into a public shell & now sells $20,000 animatronic companions with magnetic swappable faces. Meanwhile Boston Dynamics, Tesla, Figure, and every other major humanoid maker has committed to never entering the romantic companion market.

3 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • 27d ago

Gaddafi's Great Man-Made River in Libya pumps 6.5M cubic meters/day of Ice Age water that has zero recharge — 70% of the country's freshwater. The aquifer is shared with Egypt, Chad, and Sudan, with no coordination, no metering, and no enforcement. Depletion estimates range from 60 years to 1,000.

2 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • 28d ago

A 2023 Chinese experimental program found tungsten rod penetration peaks around Mach 3.5 — above that the rod fragments before full penetration. If correct, orbital kinetic weapons offer no bunker-busting advantage over conventional Mach 3 munitions, which was the entire 'Rods from God' case.

2 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • 29d ago

Mount Athos has banned women — and female animals — since 1046. It sits inside the EU, and EU gender equality law does not apply there: the 1981 Greek accession treaty specifically exempted it. The European Parliament asked Greece to lift the ban in 2003. Greece declined.

2 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • Jul 26 '26

The 1908 Tunguska airburst flattened 80 million trees and left no crater — the asteroid detonated 5-10 km up and never touched the ground. That size class, a few tens of meters, is exactly the one our surveys miss. Chelyabinsk arrived out of the sun in 2013 with zero telescopes tracking it.

2 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • Jul 25 '26

Stalin helped organize a 1907 bank robbery in Tbilisi where Bolsheviks threw bombs into a crowded square to rob a cash convoy, killing about 40 people. Most of the money was in high-value banknotes whose serial numbers the bank had recorded — so the party could barely spend what it killed for.

3 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • Jul 22 '26

In 1986 a lake in Cameroon exhaled a cloud of CO2 that flowed silently downhill and killed 1,746 people and 3,500 livestock in one night, up to 15 miles away. No fire, no flood, no wounds. Lamps were still burning. Survivors woke hours later to find their families dead around them.

3 Upvotes

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r/Today_I_Learned_This • u/derkamak • Jul 21 '26

Greatest scientist ever existed in the history of a human kind?

6 Upvotes

32 comments

r/Today_I_Learned_This • u/FullCard_1 • Jul 08 '26

TILT Trump must pay E. Jean Carroll $5m after Supreme Court denies sex abuse verdict appeal

usatoday.com

284 Upvotes

8 comments

r/Today_I_Learned_This • u/mbeinternational • Jun 24 '26

Today I learned how to use Reddit!!

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r/Today_I_Learned_This • u/unteachablecourses • Jun 22 '26

Sergeant Reckless was a Mongolian mare bought for $250 at the Seoul racetrack in 1952 — sold by a stable boy raising money for his sister's prosthetic leg. She carried ammunition for the US Marines through the Korean War, earned 2 Purple Hearts, and became the only animal to hold official USMC rank.

3 Upvotes

1 comment

r/Today_I_Learned_This • u/unteachablecourses • Jun 17 '26

Mexico City's Gran Canal was built in 1900 to carry sewage out by gravity. The city — built on a drained lakebed — has since sunk 10 meters as groundwater is pumped out. The canal now sits below its own outlet, so it needs pumps to push sewage uphill. NASA satellites measure the sinking at 2 cm/mo.

2 Upvotes

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r/Today_I_Learned_This • u/siroff-white • Jun 15 '26

The Logic Behind Asian Architecture

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79 Upvotes

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r/Today_I_Learned_This • u/Jellyfish-Klutzy • Jun 15 '26

Learn Something New Today

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159 Upvotes

4 comments

r/Today_I_Learned_This • u/unteachablecourses • Jun 14 '26

K-Dog & 8 other Navy dolphins cleared 100+ mines from Iraq's Umm Qasr port in 2003 — the 1st combat deployment of U.S. military dolphins. The Mk 7 system's biological sonar still outperforms every other system the Navy has. In 2026, the Strait of Hormuz brought military dolphins back into the news.

1 Upvotes

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r/Today_I_Learned_This • u/Creative_Life_6919 • Jun 13 '26

Today I learned.

reddit.com

1 Upvotes

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r/Today_I_Learned_This • u/unteachablecourses • Jun 08 '26

Electric eels don't just stun prey — they use the same high-voltage pulse as radar, tracking the target's precise location through the electrical return signal. Sharks detect buried fish by sensing their heartbeats. Platypuses hunt with eyes closed using 40,000 electroreceptors.

2 Upvotes

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