and you're okay with the full frontal on
this we'll let the twitterverse comment
on it hi i'm tor hansen author and
biologist today i'm here to answer your
questions on twitter this is biology
support
[Music]
and jerry peters asks are viruses alive
let me answer that question with another
question what does it mean to be alive
most biologists define life as an
organism with cells that respond to
their environment and an organism that
can reproduce itself viruses don't meet
that definition because they do not have
cells they reproduce only by co-opting
the reproductive capabilities of a
living cell yet we see viruses having a
very direct impact on our lives and the
lives of other creatures in this world
so it just goes to show us that the very
definition of life is still in some ways
open to question at sub nom nom nom asks
why are succulents such finicky little
succulent plant lives in a
particular condition out in the wild
where they have adapted to really dry
situations where they need to hold a lot
of water in their leaves and those are
difficult
conditions to replicate inside your
house which is part of the reason they
can be very difficult to keep as house
plants at hey adrienne asks seeds are
interesting who knew that when you eat
one you're eating little plant embryos
it's hard to imagine how small a seed
can be until you meet the seeds of an
orchid these come from a small orchid in
our flora called the spotted coral root
and each seed is like a moat of dust
only a few cells organized together
there are approximately one million
spotted coral root seeds in this vial
which stands in stark contrast to the
world's largest seed the double coconut
which grows on palm trees found only on
two islands in the seychelles
archipelago isolated out in the middle
of the indian ocean and a full-size
double coconut can weigh 40 pounds 11
orders of magnitude larger than an
orchid seed so ask yourself where else
in nature can you find something so
different in form that has the same
function at
arbatra01 asks does darwin's theory of
evolution apply to plants also yes at
hungley asks dumb question time do you
think archaeopteryx would have made a
good pet
this replica of an archaeopteryx fossil
hangs on the wall in my office and i
look at it every day and biologists have
been looking at this fossil for over 150
years some call it the rosetta stone of
biology because it contains so much
information about evolution and it
reveals a creature that displays
characteristics of reptiles and of birds
this is one of the first fossils that
gave people an inkling that in fact the
birds are living dinosaurs look at the
mouth of it up close you would see
little teeth it is what some people at
the time it was discovered called
evidence of a missing link if you will
evidence of evolution in progress we
know that it lived in the trees if you
look at the feathers they are like
modern feathers offset and aerodynamic
on the wings which indicates it was
soaring or flapping at the time so it
would have been a messy pet to have
around in the house knocking things over
and so forth and it might have given you
a nasty bite because it had teeth
overall it's such an important creature
that i think any biologist would love to
have one as a pet aunt john mace live
sent a picture with a question bones
found while walking in the woods any
idea of what it was bigger than my
50-pound dog you are looking at the
skeleton of a deer and if you look
closely you will see that something is
missing from that skeleton you have the
top of the skull and it so happens that
i have the jawbone from a deer skull
right here this part has teeth in the
front but if you were to go back in the
woods and look at the top of that skull
you would find just a bony plate no top
teeth on a deer they are pinch and tear
herbivores meaning they pinch the
vegetation with their bottom teeth
against that bony plate and then tear it
off so you can always tell when you're
out in your garden whether it's been a
deer attacking your favorite shrubbery
or whether it's been something like a
rabbit that makes a clean cut because
deer always leave a rough cut on the end
of the vegetation that they've been
nibbling at r.j zenith asks can dogs and
foxes be crossbred or are they too
different so dogs and foxes are in
different what biologists or taxonomists
would call genera they have a different
genus they're not closely related
they're very very distant cousins they
cannot interbreed and produce viable
offspring whereas dogs and wolves are
closely related in fact dogs descend
from wolves they were domesticated from
wild wolves only 40 000 years ago which
isn't that long in evolutionary time so
those two can definitely hybridize and
they often do
at indea elise16 asks
like how the hell did a fish just get up
one day and say i want to walk on land
and now here we are like it just
miraculously turns its gills to lungs
and can walk even though we can't say
precisely what things were like at that
critical moment that there are creatures
in the world that still display some of
those characteristics there are
creatures called lungfish which can
crawl short distances through the mud to
get from one pool to another we are all
familiar with that cartoon image of
evolution with the creature emerging
from the water and then
progressing through a series of forms
until there's a human being at the end
it's the most destructive cartoon in the
history of science because it gives us
this false idea that evolution is a
linear progression of one form replacing
the other along the path when in fact
it's much messier more complex and more
wonderful than that so yes there was
some creature that first began to emerge
from those watery depths onto land but
that led to a great diversity of
different pathways once that transition
took place at start soul asks how will
the human species evolve the future of
our species is a big question and open
to question but we know a lot about
human evolution from looking at the past
and the story of human evolution is
really in many ways the story of brain
size and each time we've seen some
increase in the capacity of our brains
biologists and anthropologists have
associated that with some change in
human behavior that allowed us to gain
more calories because brain tissue is
what physiologists call metabolically
expensive it takes a lot of fuel to run
a brain as many as 20 of our daily
calories go to fuel something that's
only two percent of our body weight so
if you want a bigger brain you're going
to have to have more calories to run it
and we've seen that through time as our
species has
adopted new characteristics new traits
new habits that have given us more to
eat those things include tool use and
social behaviors and cooking the food so
now we are at a period of time where
food for many people is plentiful
calories are plentiful one question for
future biologists then will be how did
that change the human brain at fly
behavior asks mutant corn for dinner
anyone know what mutation would likely
cause the double-sized kernels well we
don't know if it's a mutation at all
because sometimes corn or other plants
respond in strange ways like that to
disease or bacteria or fungi so we can't
say what's making those kernels large in
that situation but whoever gets that ear
for dinner will have a bonus ed cheryl
roefer asks can crispr save bananas from
the fungal threat serious question for
biology tweets it's a serious question
for anyone who loves bananas the common
banana that we buy in the grocery store
is called the cavendish banana and
unlike many other fruits in the store
the cavendish bananas are not produced
from seeds and traditional crop breeding
a banana plant produces offshoots that
are easy to separate from that plant
that are clones of the banana plant
itself so if you find a banana that has
the characteristics that will be
successful commercially it lasts a long
time it has good flavor you can ship it
around the world to grocery stores that
is a truly valuable fruit and that's why
the cavendish banana is so popular and
why it's produced via cloning so when
there is a threat like this fungus that
lives in the soil and destroys the
cavendish banana plant they're all
susceptible to that fungus in the same
way crispr is a tool in molecular
biology that's used for turning on or
turning off particular genes within the
genome of a species so if there is a
gene currently turned off in the
cavendish banana that could be turned on
again to provide resistance that is a
possible solution to this problem at ac
ella asks friday debate in the office do
plants grow from the bottom or the top
well typically plants grow from the top
but there are situations that we're very
familiar with where that growing part of
the plant is lowered down and we see
that in our own lawns grasses have
evolved to grow from the bottom in
response to grazing by animals and more
recently by the cutting of lawn mowers
so that that leaf that you see when we
cut it off will be replaced from below
but most plants like a fir tree or an
apple tree are growing from the tips of
their shoots at k baumlier asks how does
climate change affect wildlife we often
summarize the impacts of climate change
on plants and animals with the acronym
mad short for move adapt or die
and we see examples of all three of
those playing out in nature all around
us between 25 and 85 percent of species
on this planet are now moving shifting
their ranges in response to climate
change looking for the temperatures and
conditions that they're used to many
other species are adapting by changing
diets or behaviors to try to cope with
this crisis and yes some species are
dying and going extinct and we also see
species struggling to
adapt and adjust their relationships to
one another a fascinating example
recently out of gabon in africa where
for the first time scientists observed
chimpanzees attacking a group of
gorillas and in fact even killing one of
the gorillas one of the reasons this may
be happening one of the theories is that
there is now a shortage of fruit and
other foods for those creatures in that
forest because of climate change
creating a new
hyper-competitive environment for those
two species that used to coexist
peacefully at nico miller asks blue eyes
are weird
what is af i'm sorry how do i
oh as
can i say that or what do i say at nico
miller asks blue eyes are weird af like
honestly how does a mutation like that
even happen mutations in biology occur
in the dna when it's being copied it's
not a perfect process mistakes are made
often times those mistakes lead to new
features in the organism usually they're
not very useful and they disappear over
time but sometimes they can impart a
benefit and they persist this is one of
the fundamental ways that new traits are
introduced into the evolutionary process
blue eyes were introduced in that way
fairly recently in human evolution they
have persisted but no one's quite sure
yet what the advantage of blue eyes may
be
tara luzuriaga asks how do extinct
species come back to the world short
answer they don't they're extinct but
there are efforts underway now to try to
recreate or bring back some extinct
species like the woolly mammoth from
ancient dna it's still a work in
progress a long way off but some experts
are working on that very question
lauren r peters asks if we have evolved
from monkeys why are they not extinct
when new species evolve it's not
necessary for them to replace the
species they evolved from in fact it's
more common for new species to exist
side by side with many closely related
species atkaru1402
asks is the number of genetically
different human beings that can be
formed finite people are often curious
if there might be a doppelganger or
someone almost exactly like them out
there in the world today or at some
point in history and the fact is we can
be pretty close genetically but every
individual is indeed unique when you
consider the number of genes in the
human genome 20 000 30 000 but also
considering the number of base pairs in
those dna molecules you're talking about
billions of different combinations
on top of that it's not just the genes
themselves that are crucial but how
those genes are expressed all of those
things can be different among
individuals we're not going to run out
of unique individuals anytime soon at
ibis journal asks what makes hashtag
penguin feathers ice proof they're not
just ice proof they are waterproof
structurally waterproof and biologists
still aren't sure exactly how that works
but if you look microscopically at the
veins of those feathers you see that
they trap all sorts of small air pockets
and it may be that air preventing water
moving through the feather that
intricate feather vein has thousands and
thousands of individual places where the
feather surface is pushing against the
natural surface tension of the water
either way you don't have to worry about
penguins getting wet on their skin et r
heisman asks what are some of your
favorite unsolved mysteries in biology
interpret however you like one of the
great mysteries that we've really only
discovered somewhat recently is just how
mysterious our own genome is when the
human genome project sequenced our dna i
think many people thought we would have
the recipe book for how to make a human
being but it turned out to be far more
complicated than anyone thought because
it's not just the sequence of the genome
but it's the shape of the molecule it's
the genes it's the patches of dna around
the genes that control them it's all
sorts of things that combine to
see how those genes are expressed and
what makes us human but you don't even
have to go into molecular genetics to
find mysteries they're all around us a
constant reminder that there's so much
to learn about ourselves and about
nature consider something as familiar to
all of us as yawning we still don't
understand why people yawn at michael
mccaller asks how did darwin know all
that evolution stuff he didn't know he
learned it as he traveled and explored
his world because in the 19th century it
was still widely assumed that everything
was created very recently if you will
by the hand of god and so darwin was
fascinated by geology and how there were
species in the rocks in fossils that
were no longer present in the modern
world he came up with the idea of
evolution by natural selection would
help explain how things changed through
time and how you had this great
diversity of life on the planet and it
was a radical idea at the time he sat on
it for years and years before finally
publishing his theories because he knew
they would be controversial at lonely
kino asks what is bioethics the ethics
of biology the answer is yes and we need
to think about the ethics of biology as
our ability to do more and more
develops over time technologically we
have the ability now to change dna we
have the ability to combine species in
new ways so we must constantly ask
ourselves not only can we do these
things but should we so those are all
the questions for today and we've
covered a lot of ground thank you for
watching biology support