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老虎 大猩猩 犀牛 看来现在已有许多动物濒临灭绝
Tigers, gorillas, rhinos, it seems like there are a lot of animals on the endangered species list these days.
But we know how to clone animals.
So if the problem is too few rhinos,
and if we know how to make more rhinos
problem solved, right?
Well,there actually are people working on cloning endangered animals.
But it is not as easy as you might think,
and in the end it still won’t fix the problem
that made those species endangered in the first place.
The first mammal cloned from adult cells was Dolly the sheep back in 1996,
and since then scientists have cloned a lot of different things,
比如猫 狗 甚至猴子
like cats, dogs, and even monkeys.
And it didn’t take long for endangered animals to get on that list.
例如 21世纪初 研究人员成功克隆了印度野牛
In the early 2000s, for example, researchers cloned a type of wild cow called the gaur.
And they went on to clone other endangered cattle, wild sheep
and even an extinct wild goat.
But as cool as these achievements were,
none of them ended up really increasing the species’numbers.
That’s because, despite what movies might suggest,
you can’t just order up an army of clones.
To clone something, you typically need more than just some DNA from the original creature.
You also need an egg cell to put that DNA into to create an embryo.
Then that embryo needs to be implanted in a surrogate mother to develop.
You can’t just do this in a petri dish.
While that all might sound straightforward enough,
getting those eggs in the first place can be difficult and risky for the animal.
To know how to get eggs,
you need to know a lot about that specific animal’s reproductive biology,
like when they ovulate, or grow andrelease egg cells.
Humans generally ovulate in regular frequent cycles,
but not all animals do.
Pandas only ovulate once a year, for example,
and there are animals like cats that only ovulate after mating.
We can sometimes use hormone injections to kick start ovulation,
but each animal may need different doses or a different mix of hormones.
And then you still have to get the eggs.
Take rhinos, for example.
Like you try convincing a 1,700 kilogram ovulating rhino to let you collect eggs,
from inside her using a custom-designed,one-and-a-half-meter-long device.
I won’t,I mean sure you can sedate her.
Which is definitely what the researchers do.
But sedation also carries risks.
All and all, getting eggs from animals may involve multiple hormonal injections
and the use of anestheticsor surgical procedures,
and not every individual animal is healthy enough to undergo all that.
And also, you need to collect a lot of eggs.
The DNA-egg cell fusion doesn’t always work right,
so for each viable embryo, you might need hundreds of egg cells.
And even if you go through all of that,
you still need surrogates to carry the pregnancy.
Like collecting eggs, that requires knowledge about the animal’s reproductive biology,
as well as lots of healthy female animals;
more than just the number of clones you want to make.
Because unfortunately, not every implantation takes and develops into a healthy offspring.
For plentiful species, or ones we know really well,
like cows or sheep, those might not be big problems.
But for endangered species, like tigers or rhinos,
there may not be enough female animals to work with.
The good news is that there are ways to kind of cheat.
You can sometimes use eggs or mothers from more common closely related species, for example.
the baby gaur’s surrogate mom was actually a regular cow named Bessie.
Because of course, all cows are named Bessie, apparently.
But hybrid embryos can haveextra problems during development.
Scientists are working on an alternative to all this:
A way to make eggs and sperm by genetically reprogramming frozen tissue samples.
So one day we might be able to make a lot of eggs without needing a lot of female animals.
But that’s still in the very early stages and the process will likely need to be customized for each animal.
Now it’s possible that we might figure out how to solve all of these challenges.
But even if we could clone any animal we wanted,
it might not be the fix we were looking for.
For one thing, even though cloning might increase the number of animals
You could still end up with a loss of genetic diversity
because they’d all be genetically identical.
That’s bad because the population couldeffectively become inbred,
which can leave them vulnerable to diseases or genetic disorders.
If you have frozen tissues from a lot of different individuals,
you might be able to avoid this issue
or even reintroduce genetic variation that’s been lost,
but that will depend on what you’ve stockpiled.
The real problem with cloning endangered animals
is that it won’t stop the poachers, habitat loss, or myriad other things
driving these species extinct in the first place.
Cloning is very expensive,
而且研究者指出 更划算 更有效的方法
and some researchers have pointed out it’s probably cheaper and more effective
to spend that money on fighting poaching, creating new nature reserves,
or other, more traditional conservation efforts.
Still scientists working on cloning remain optimistic
that could one day become really useful tool for conservation,
like to reintroduce lost genes
or last lifeline to save species whose numbers have dwindled to just a handful.
But for now, we’ll have to make all of our tigers and rhions the old fashioned way
Cloning animals in the real world super tricky,
but cloning pictures of animals is something any one can learn to do well
especially with the little help from one of the amazing Photoshop classes offered by Skillshare.
But if you really want to up your Photoshop-art game,
you might want to check out this Skillshare course by lifestyle journalist Helen Bradley
on how to make surrealist collage effects.
In it, Helen explains how you can use different Photoshop tools
to split apart an image and make really wacky art,
sort of like the prints by the artist featured in the episode, Julia Geiser.
What I love about this class is that, as the title suggests,
Helen goes through everything clearly and quickly,
so you really can take the class over your lunch break,
And Helen has a bunch of otherquick courses on Skillshare,
so you can try your hand at making stylish doodles or drawing furry creatures.
现在 Skillshare 给科学秀的观众两个月的免费的使用权
Right now, Skillshare is offering SciShow viewers 2 months of unlimited accesses for free
And they have more than 20,000 classes to choose from,
so no matter what hobby you want to pursue,
there’s probably a Skillshare course for you to take.
And you’ll be supporting SciShow while you do it.
You can follow the link in the description to check it out!