This week on the channel +2M views this week

Green eyes complicate Be Smart's question about green mammals

Joe Hanson's only new upload explores fur pigments, sloth algae and the unusually colorful turaco.

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Be Smart Story of October 30, 2026Trari Newsroom

Why this story? The channel's weekly summary: what went up this week, what is drawing views now, and where the channel stands among similar channels.

Why are there no green mammals?

Sloths don't get credit: their green tint comes from algae living in their fur. Green eyes don't qualify either, Joe Hanson says, because their appearance comes from light scattering through pigment. That second distinction has become the talking point beneath Be Smart's "Why are there no green mammals?"

The short explainer moves from mammals' two main fur pigments to the more inventive ways other animals achieve green. Hanson singles out turacos for producing an actual green pigment, then explains how structures and combinations of colors do the job elsewhere. His evolutionary explanation is that many mammalian predators cannot readily distinguish red from green, reducing the pressure to develop green camouflage.

Viewers are pressing on the definition, rather than simply offering more animals. Several ask why structural color counts for feathers or frogs but disqualifies green eyes. It's a useful question to leave beside the video: are we talking about a green pigment, or an animal that looks green?

The week's only upload has reached roughly 634,000 views and is comfortably the channel's busiest video right now. Behind it, last week's investigation of AI's environmental costs continues drawing viewers, along with the older genetic-detective story about HIV's origins.

Be Smart added about 10,000 subscribers over seven days, while its daily viewing pace is well above usual. Among nearby science channels, SciShow also had a substantial viewing week; minutephysics and Real Engineering are currently quieter than their usual daily pace. For Hanson, the new burst of attention returns to familiar territory: the channel's most watched regular upload is "Why Is Blue So Rare In Nature?" Color keeps supplying deceptively simple questions.

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Where next?

Also in Science and experimentsA video worth knowingHank Green tests RFK Jr.'s measles explanation against vaccination trendsHis commentary contrasts Kennedy's account of pandemic disruption with falling MMR coverage and the demands of containing a highly infectious disease.Channel: Hank Green · Story of October 31, 2026

A different discovery todayVideo taking off 47x its usual first dayDiane Sawyer's Patrick Stewart interview closes World News TonightThe October 29 edition also covers Alaska's Senate probes and a Pentagon firing, but its comment section belongs largely to the actor.Channel: ABC News · Story of October 31, 2026

What viewers say

So why do green eyes not count because of being blue light scattered by physical structures, yet all of these other animals that are green because of physical structures or other color mixing count as being green?
@mykel723See it on YouTube
The reasoning for why green eyes aren't green is the same reasoning you used to say green frogs and chameleons are green.
@zaph-oddSee it on YouTube
A golden retriever after rolling in the freshly mowed grass.
@Sessa107See it on YouTube

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