Recent comments in /f/askscience

Boring_Ad_3065 t1_j4wxbyf wrote

Reply to comment by cheekychessie in What specifically keeps viruses from moving from human to animal or vice versa in most cases? by cheekychessie

Adding on to this, some viruses are really good at jumping species. Influenza is one example, hence why you hear of swine flu and avian flu, but different variants can infect seals, cattle, dogs, horses, etc. It doesn’t help that humans raise billions of pigs and chickens for food that are kept in very close, not great conditions, so there are many opportunities to interact with large populations of sick animals. The fear of spreading is why you hear of culls of millions of animals sometimes. This also happened with minks and COVID.

HIV descended from SIV, and was most plausibly introduced to humans when a hunter was harvesting bushmeat, a bloody process, and cut themselves.

It’s important to note that just because viruses can cross species, they can be more or less deadly and transmissible. Typically early versions of viruses aren’t well adapted to new hosts. COVID is likely harmless in bats (who carry many viruses), and clearly deadly in humans, while being poorly adapted to dogs. For COVID, this is due primarily with how our respective ACE receptors are. Additionally even within roughly similar viruses there’s variance. MERS, another coronavirus carried by camels is much deadlier than COVID at ~37% of cases but thankfully far, far harder to transmit.

Finally it’s not all bad for humans. We eradicated smallpox in part because someone noticed that milkmaids were practically immune to it. Cowpox is similar enough that it conferred strong immunity to smallpox, while being much more mild.

A caveat - evolution in general, but for viruses in particular doesn’t “seek” anything. Viruses don’t even meet all typical criteria for being alive, and their evolution is purely a numbers game, with a single infection generating upwards of trillions of viruses, and then “hoping” it comes in contact with another suitable host. Viruses are also messy, and some can share genes very readily. Influenza is a prime example.

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aspheric_cow t1_j4wwqpp wrote

Reply to Whats stopping us from sending a probe into a black hole if we haven't already? by stealth941

  1. There aren't any nearby black holes.
  2. We don't have the technology to send a probe to any black hole. We don't even have the technology to send a probe to another star, and the closest black holes are hundreds of times further still.
  3. Any probe we send near a black hole will be ripped to shreds by the tidal force. (Unless maybe if it's a supermassive black hole, but I think the closest one is at the center of our Galaxy which is 28,000 light-years away.)
  4. Even if we had the technology to send an interstellar probe, it would be a lot more valuable to send it to star systems with potentially habitable planets, or star-forming regions, or maybe a newly formed star with a protoplanetary disk, or maybe a really old globular cluster, or a late stage star that may go supernova any time, etc, etc.
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tandjmohr t1_j4wuw43 wrote

Reply to comment by icbmike_for_realz in Extinction of the Dinosaurs: What did I miss? by cakedayCountdown

In this specific case they are referring to Flood Volcanism. The Deccan Traps (I probably spelled that wrong) are a large igneous province in India where, about the same time as the Dino asteroid (geologically speaking), large cracks opened in the crust and absolutely immense volumes of basaltic lava poured out in flows hundreds of feet thick covering thousands of square miles one on top of the other. The cumulative depth of these flows are measured in miles.

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venom121212 t1_j4wrp6e wrote

Reply to comment by cheekychessie in What specifically keeps viruses from moving from human to animal or vice versa in most cases? by cheekychessie

It's more like covid evolved in its host species to a form where it was able to affect humans.

To oversimplify things:

Picture a virus as a really funky key. Your cells (animal cells) are covered in funky looking locks. These locks are meant to allow good things in while generally keeping bad stuff out, all throughout your body. When a virus mutates, it is finding a way to spread more efficiently and effectively. One of these methods is by changing binding protein shape to fit more locks.

Similar situation with swine flu, avian flu, and many other zoetic viruses. We keep an eye on which animal viruses are getting dangerously close to making the human jump by taking animal cell lines, replacing the receptors (locks from earlier) with human versions, and then seeing if the virus is able to bind and replicate.

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