--- title: Why Birds Can Fly over Mount Everest | daily.dev description: Bar-headed geese can fly over Mount Everest at 28,000 feet because birds have unusually efficient lungs, inherited from dinosaurs. Unlike mammals, birds have a... canonical: https://daily.dev/posts/why-birds-can-fly-over-mount-everest-ar5dsotv5 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Why Birds Can Fly over Mount Everest | daily.dev og:description: Bar-headed geese can fly over Mount Everest at 28,000 feet because birds have unusually efficient lungs, inherited from dinosaurs. Unlike mammals, birds have a... og:url: https://daily.dev/posts/why-birds-can-fly-over-mount-everest-ar5dsotv5 og:image: https://api.daily.dev/og/posts/Ar5dsoTV5.png og:image:alt: Why Birds Can Fly over Mount Everest og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Why Birds Can Fly over Mount Everest **[Hacker News](https://daily.dev/sources/hn)** · 17 min read · 0 upvotes · 0 comments ## Summary Bar-headed geese can fly over Mount Everest at 28,000 feet because birds have unusually efficient lungs, inherited from dinosaurs. Unlike mammals, birds have a separate air intake and exit point plus air sacs and hollow bones, so oxygenated air flows through their lungs in one direction on both inhale and exhale. This essay by Walter Murch traces that lung design back to the Carboniferous period, when undigested lignin from land plants caused atmospheric oxygen to spike above 30 percent, then fall to about 12 percent by the end of the Permian, killing 95 percent of life on Earth. Dinosaurs evolved super-efficient lungs to survive the low-oxygen aftermath. The essay ends by connecting the fossil fuels that formed from that buried lignin to today's climate change. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How are bird lungs different from mammal lungs that lets birds fly at such high altitudes Bird lungs have a separate entry and exit point for air, unlike mammal lungs which use the same opening for both. Birds also have air sacs and hollow bones that store oxygenated air. This means air flows in one direction through the lungs whether the bird is inhaling or exhaling, constantly pushing oxygen in and carbon dioxide out, making the system far more efficient than mammalian lungs. _Curious minds digging into evolutionary biology topics like this can follow more science deep dives on daily.dev._ ### How high have bar-headed geese been seen flying over the Himalayas Bar-headed geese have been observed flying as high as 28,000 feet, high enough to pass over Mount Everest. They make this migration annually between wintering grounds in central India and summer breeding areas in Kazakhstan or Mongolia, crossing the Himalayan range which separates the two regions. _Readers tracking unusual animal physiology facts can find similar science stories on daily.dev._ ### Why did atmospheric oxygen levels crash at the end of the Permian period Oxygen fell from above 30 percent during the Carboniferous period to around 12 percent by the end of the Permian period, after fungi evolved an enzyme that could finally decompose lignin in dead trees, which had previously piled up undigested for about 100 million years. That decomposition process consumed atmospheric oxygen rapidly, and the resulting low-oxygen atmosphere killed 95 percent of life on Earth, the largest extinction event in its history. _People exploring how ancient Earth events still shape today's ecosystems can find more context like this on daily.dev._ ## Community take How the wider developer community reacted, aggregated from 1 discussion and 38 comments across hackernews (as of 2026-10-29). **TL;DR:** Discussion mostly appreciated the article's storytelling (and was delighted to learn it was written by famed film editor Walter Murch), while several commenters pushed back on scientific details like the lignin/coal theory and the claim about oxygen flammability, and others debated the closing point about fossil fuels and climate. **Sentiment:** 40% positive · 45% mixed · 15% skeptical **The case for** - Many found the article well-written and fascinating, especially the connection between dinosaur lung evolution and coal formation. - Several were excited to learn the author was the renowned film editor Walter Murch. - Some appreciated the broader framing of energy ultimately originating from the sun via plants and fossil fuels. **The pushback** - Some pointed out that the lignin-digestion gap theory for coal formation is no longer the scientific consensus. - One noted only fungi, not bacteria, break down lignin, and only in aerobic conditions. - Commenters corrected the article's claim that high oxygen levels would make the atmosphere flammable, noting oxygen is an oxidizer, not a fuel itself. - One felt the piece leaned too heavily on teleological reasoning. **By community** - hackernews (mixed): Appreciation for the writing and the surprise authorship by Walter Murch mixed with pointed scientific corrections about lignin, coal formation, and oxygen flammability, plus a tangent into climate/energy policy debates. **Hottest debate:** Whether the article's lignin-digestion-gap explanation for Carboniferous coal formation is still scientifically accurate. **Open questions** - What is the current scientific consensus on why so much coal accumulated during the Carboniferous if the lignin-digestion-gap theory is outdated? **Highlights** > The part about coal coming from dead trees during a window of time before bacteria evolved lignin digestion is no longer the scientific consensus. Such bacteria existed earlier; not all coal is high lignin; and coal still formed later. Too bad; it was a lovely story! > — [adonovan on hackernews · 2 comments](https://news.ycombinator.com/item?id=50282477) > It's not bacteria. The only organisms that can digest lignin are fungi, and they do it by blasting lignin with peroxides. As such, this works only in aerobic environments (not swamps). > — [cyberax on hackernews](https://news.ycombinator.com/item?id=50282590) > That theory is not really disproven, even if it was not the only reason for the huge accumulations of coal during the Carboniferous. Coal has been always forming later, even today, but never in such quantities, because later it required much luckier conditions for the wood to not be decomposed by fungi. The climate and the position of the continents during the Carboniferous must have contributed to the accumulation of coal, i.e. it is likely that a much greater percentage of the surface of the Earth was covered by some kind of swamps with warm climate, where plants were abundant and dead wood could submerge and be protected from decomposition, but this still does not appear to be able to explain the so great discrepancy in the amount of accumulated coal. The most likely explanation is that all factors must have contributed, the conformation of the continents, the climate and the low abundance or absence of wood-digesting fungi, or perhaps there already were wood-digesting fungi, but their enzymes were not as efficient yet as those of later fungi, so they could decompose only a small part of the wood before it was buried in sediments. > — [adrian\_b on hackernews](https://news.ycombinator.com/item?id=50285415) > > at 43 percent a lightning strike will cause the entire atmosphere to ignite since it is so high in flammable oxygen Good article except oxygen is not flammable. Oxygen is the stuff that makes other stuff flammable. > — [dreamcompiler on hackernews · 2 comments](https://news.ycombinator.com/item?id=50284610) > Written by Walter Murch?? Like, the guy who is considered maybe the best editor and sound designer of all time, who was nominated for 9 Academy Awards, and won 3??? (Editing perhaps second only to Thelma Schoonmaker.) > — [antics on hackernews · 1 comments](https://news.ycombinator.com/item?id=50282391) **Source threads** - [hackernews](https://news.ycombinator.com/item?id=50220975) · 141 points · 38 comments ## Similar posts on daily.dev - [Early life may have breathed oxygen earlier than believed](https://daily.dev/posts/early-life-may-have-breathed-oxygen-earlier-than-believed-aqnodsz57) · MIT Technology Review · 0 upvotes · 0 comments - [Some early life forms may have breathed oxygen well before it filled the atmosphere](https://daily.dev/posts/some-early-life-forms-may-have-breathed-oxygen-well-before-it-filled-the-atmosphere-gd3dtep5o) · MIT News · 0 upvotes · 0 comments - [V Formation Flying Of Birds Is Explained By A Minimal Wake–Vortex Model](https://daily.dev/posts/v-formation-flying-of-birds-is-explained-by-a-minimal-wake-vortex-model-g6sb3en8n) · Hackaday · 0 upvotes · 0 comments - [What happens when environmental change outpaces life’s ability to adapt?](https://daily.dev/posts/what-happens-when-environmental-change-outpaces-life-s-ability-to-adapt--kvpdkfnbh) · MIT News · 0 upvotes · 0 comments - [How Geology and VFX Helped Rebuild Prehistoric Earth for The Dinosaurs](https://daily.dev/posts/how-geology-and-vfx-helped-rebuild-prehistoric-earth-for-the-dinosaurs-efrrcmsrv) · 80 LEVEL · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/why-birds-can-fly-over-mount-everest-ar5dsotv5) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Why Birds Can Fly over Mount Everest","url":"https://daily.dev/posts/why-birds-can-fly-over-mount-everest-ar5dsotv5","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/why-birds-can-fly-over-mount-everest-ar5dsotv5"},"datePublished":"2026-10-29T00:58:11.621Z","dateModified":"2026-10-29T08:31:32.020Z","description":"Bar-headed geese can fly over Mount Everest at 28,000 feet because birds have unusually efficient lungs, inherited from dinosaurs. 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