Shadowing Practice: Biggest Breakthroughs in Biology and Neuroscience: 2025 - Learn English Speaking with Video

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For millennia, we humans have set ourselves apart from the rest of the animal kingdom, pointing to cognitive abilities that we alone possess.

Like the use of tools.

Or planning and problem solving.

But over the last half century, this perception has changed.

Of course it has been observed that other animals have interesting and sophisticated mental lives as well, and in particular birds among vertebrates.

This is something that goes beyond just simple reflexive behaviors.

And there are many different bird species which are very clever, quite intelligent.

In many aspects and in many tasks, they can be comparable to children, to kids up to seven years old.

So is bird intelligence just a less evolved form of human intelligence?

Or is it something else entirely different?

Now, a trio of recent papers published in the journal Science have revealed an intriguing answer.

For the longest time, we thought the neocortex is like the structure you need to be intelligent.

Until the middle of the 20th century, many neuroanatomists assumed that birds couldn't be all that smart.

Because they do not have the structure that we use in our brains to become intelligent.

Avian brains lack anything resembling a neocortex, the layered and highly-ordered outermost structure in humans and other animals where communication and higher reasoning reside.

We needed to conciliate these two ideas that birds, in many cases are very intelligent, but they do not have that neocortex.

However, birds do have something called the dorsal ventricular ridge or DVR.

These are a huge mass of neurons.

Neurons in birds are very small and they are packed.

The density of neurons is high.

Very, very high, much higher than in any mammalian species.

In the 1960s, the neuroanatomist Harvey Karten observed a functional similarity between the mammalian neocortex and the avian DVR.

Karten postulated that neural circuits of the DVR are homologous, so have a common origin.

But decades later, anatomist Luis Puelles drew a different conclusion.

He found that the two structures, the neocortex and the DVR, develop in different parts of a sub-region of the brain called the pallium.

Which is the most anterior region of the of the developing vertebrate brain that looks like a hood, like a cup on top of the rest of the brain.

So the question remained...

did these brain structures, the seats of vertebrate intelligence, share the same origins, or did they evolve independently?

The only way to reconcile these different views on brain evolution is to look at circuitry and development and cell-type identity all together.

And this is what these studies have achieved collectively.

In 2025, a collaboration of international researchers released the results.

Using a combination of powerful molecular techniques.

The teams were able to answer the question at the cellular level.

We generated a cell type atlas of the avian pallium.

Then used this to compare to similar data from mammals.

And this way we could basically find out whether certain cell types actually are homologous, meaning they were present in the last common ancestor, or did they evolve independently in the two lineages?

Evidence suggests that birds and mammals last shared a common ancestor 320 million years ago, an ancient relative akin to a modern day lizard.

What we found, the developmental programs giving rise to these different circuits is not the same.

Therefore, they evolved separately.

In the mammalian neocortex and in the bird DVR, they actually started out from different cell types in the last common ancestors. In the last common ancestor, one was like in the dorsal region, one was in the ventral region.

And then over the course of evolutionary time, those cell types became similar.

And the research has revealed a more universal force of nature at work, a phenomenon known as convergent evolution.

The circuits are strongly similar, but they are not developing in the same area and they are not using the same neurons.

Evolution found the same solution using different tools.

This is a case of convergent evolution, and there are many, many cases of, convergent evolution.

Other examples of convergent evolution include unique forms of winged flight in birds and bats.

Or the evolution of camera-like eyes in both octopuses and mammals.

This is a convergence of intelligence.

Evolution found two ways to make animals intelligent, birds and mammals.

And they found it following two different evolutionary trajectories.

All these pieces together paint a different picture than what both Karten and Puelles, and you know, their colleagues in the schools of schools of thought have been painting.

I think they tell us that this is a more complex story, but also that the debate is largely settled, I will say.

In the conventional story of conception, a sperm's mission is simple - deliver the father's share of his genes to the egg.

All dad is really needed for is to just be a carrier of the paternal copy, so one half of the DNA, so one half of the genome.

But it turns out, this story about a sperm's role in inheritance may be more complex.

Environmental stressors can somehow leave a mark on the sperm and transmit traits from the father to the offspring.

And in the traditional sense, this is not possible because the DNA should be read only.

New research in mice has revealed that molecular records of a father's lifestyle can hitchhike along, producing similar traits or phenotypes in the next generation.

This has been demonstrated for examples of diet, stress, exercise, and so almost a completely new layer on heredity.

This is an independent code, beyond the DNA sequences alone.

In adult males, a sperm's journey begins in the testes, where reproductive cells divide and mature.

The sperm is constantly being made anew.

Half of the father's genes are packed tightly inside the head of each sperm.

In the 1880s, German biologist Auguste Weissmann wrote a treatise backed by experiments on mice that concluded a barrier exists between the heritable reproductive cells and the rest of the body.

There must be something blocking the environments or exposures.

This was named the so-called 'Weismann Barrier.' And really that was kind of dogma for really almost 100 years.

However, over the last two decades, a growing body of evidence has shown that this barrier, in fact, can be breached.

A father's diet, stress, exposure to toxins, including drugs and alcohol, have been shown to impact offspring.

And so really one of the landmark papers that was published in 2010 from Oli Rando's lab demonstrated that if you feed male mice different diets, you can get different metabolic phenotypes in the progeny that are associated with those diets that dads ate.

But until very recently, potential mechanisms for how these traits might be transmitted have remained up for debate.

One leading candidate is RNA, single-stranded nucleotide sequences that perform an array of biological roles, from building proteins to regulating cell function by turning certain genes on or off.

Small regulatory RNAs have the ability to regulate gene expression at many different levels.

RNA have also been found in the part of the reproductive system.

Where sperm mature, packaged inside what's called extracellular vesicles.

And we know this extracellular vesicles, they carry DNA.

They carry RNA. They carry proteins.

They can indeed transmit information.

In theory, RNA produced by a father's environmental exposures travel in the bloodstream and fill these extracellular vesicles, which then fuse with the sperm to deliver their molecular messages to the awaiting egg.

And the idea would be that these are delivered during fertilization.

So to change how early embryonic gene expression occurs and then leads to changes in development and phenotypes.

In November 2025, Chinese researchers published a study on exercise that provides the strongest evidence yet of RNA's role in transmitting heritable phenotypes.

This paper also really goes a long ways to show that its RNA and sperm.

They show it many different times.

The team trained father mice on a treadmill for two weeks and bred them with sedentary females.

They found that the male offspring were also more physically fit.

I think one of the most exciting part is that this example is is deeply adaptive.

It's just just like, that the father is sending a message to the environment is tough.

You have to be a tough to survive.

So how could this trait be passed down?

The researchers identified a specific set of microRNAs in both the sperm and the fertilized egg, which are connected to the regulation of genes that increase metabolism and muscle function in adults.

This is cool, because to me it's really the first mechanistic link of something very early actually being sufficient for the phenotype later.

However, despite the significant new evidence presented by the exercise study, many molecular mysteries remain.

We have to define the mechanism of what's going on, what is going on after fertilization?

What are these RNAs and sperm doing after fertilization to change early development?

They're impacting gene expression.

Although not confirmed in humans, the new research may be reason enough for potential fathers to think twice about their lifestyle choices.

We do not know in full how it works, but there are so many evidence tell us this can have an effect.

So why not?

As a father to be, you should probably be as healthy as possible.

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Right? And I mean, I'm kind of a newish father and like yeah, that's definitely the case.

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Whether you know these choices, right?

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Your environmental exposures or your kind of behavioral choices impact your progeny adversely, I think it's still debatable.

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What do ancient enzymes, squid shapes, and European languages have in common?

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These three systems - the biomolecular, the morphological, and the linguistic.

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These different granularities of life might be connected through some frameworks.

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In 2025, a young researcher published a new mathematical model that describes similar spikes in the evolutionary histories of these very different systems.

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We're looking at a rapid transition in the evolution, not something which happens gradually.

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This work bolsters a long-controversial theory known as 'punctuated equilibrium', which posits that new species are formed during relatively sudden bursts rather than through gradual change over time.

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I have been fighting for this stuff for 50 years.

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The explosive evolution is being found all over the place.

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For the last century and a half, Charles Darwin's writings on evolution have loomed large.

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The message that was left by Darwin was a gradual change through time.

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And that's inevitable given the mechanisms of natural selection that he formulated.

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Natural selection occurs when organisms accumulate random genetic mutations, leading to variation in traits across a population.

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Changes just build up gradually over time, they accumulate.

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Some of those traits may provide individuals a survival advantage, which can eventually lead to the splitting of lineages.

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But in 1970, paleontologists Niles Eldredge and Stephen Jay Gould had a new idea.

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In the fossil record, they rarely saw the kinds of intermediate species they would expect from gradual evolution.

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To describe this phenomena, Gould coined the term 'punctuated equilibrium.' Really is so graphic about what it is.

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The equilibria refers to the great stability that you mostly encounter if you just randomly sample things.

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They're the same as they were yesterday and will be for another million years type a thing.

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But every once in a while there's an event.

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New species suddenly appear at the nodes of the evolutionary tree, where one lineage branches off from the others.

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And so you've got two things that now differ from one another quite a bit, but there's no sort of gradual change from the ancestor to the descendants.

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It seems to have happened rapidly. Bam!

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It's almost like it's instantaneous.

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Evolutionary biologist Jordan Douglas didn't set out to examine punctuated equilibrium.

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The project I was working on was, how did life learn the rules to compute its own molecular synthesis?

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Douglas was analyzing enzymes called aminoacyl-tRNA synthetase, which are essential to building proteins.

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Forms of these enzymes have existed since the emergence of life on earth, nearly 4 billion years ago.

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They come in families and so we were interested in how those families evolved.

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But as I was studying the system, I started to realize that if we're going to model this appropriately, computationally, we need the right kind of methods behind it.

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So Douglas used computational tools and Bayesian analysis to construct phylogenetic family trees of the enzymes in his database.

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With these trees describing the relationships between these entities.

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The lengths of the branches are describing the time that these things have been apart from one another.

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In his model, Douglas saw evolutionary spikes of rapid separation at the nodes, or branch points, where enzyme families splits.

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What we call 'saltative branching.' Saltative comes from the Latin word for leap.

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So it's like a leaping branch.

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Saltative branching is followed by rapid, independent evolution of the new branches.

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You have an unusual mutation which changes a whole lot of things, doesn't destroy the system, but then the other parts of the system quickly readjust.

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And after this burst of evolution, the system stabilizes.

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The model also revealed branches that evolved and went extinct.

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Eventhough they're gone now, the fact that they used to exist has still left behind some sort of footprint on the lineages that have survived.

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Douglas' model successfully described the evolution of his enzyme.

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But he wondered, what might it reveal in datasets from other systems?

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So we tested this on 13 different biological systems.

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We were not entirely sure what to expect.

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We looked at cephalopods, for example octopuses, squids, cuttlefish, etc..

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The model predicted the sudden bursts in the change of body shapes found in the evolutionary history of these cephalopods.

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Surprisingly, Douglas' model also predicted evolutionary spikes in the family tree of Indo-European languages.

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The more datasets we started playing with, the more we realized, okay, this process must be happening quite often.

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Saltative branching seemed to be everywhere, but it may not represent the entirety of the evolutionary story.

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What we really need is to test this on more datasets.

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Just kind of figure out how often is this process occurring, but also what proportion of total change can be explained by this process?

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And what proportion is explained by gradualism?

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For Eldridge, Jordan's model was a welcome validation.

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This is fantastic, you know.

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So that was my feeling when I saw the paper.

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I said, I think this is really basically a tipping point.

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Vocabulario y notas de pronunciación para esta lección

Esta lección de conversación de nivel C1 se basa en el vídeo “Biggest Breakthroughs in Biology and Neuroscience: 2025”. Este vídeo tiene 159 frases y 2423 palabras para practicar shadowing. La parte hablada dura 15:35. El hablante habla a un ritmo natural de unas 155 palabras por minuto, cercano a una conversación cotidiana. Solo el 76 % de las palabras está entre las 3.000 más comunes del inglés, por lo que el vocabulario es exigente.

Vocabulario clave de este vídeo

Las 15 palabras más avanzadas del vídeo, con su pronunciación y significado:

Palabra	Pronunciación	Significado
evolutionary adjetivo	/ˌiː.vəˈluː.ʃən.ɛɹ.i/	evolutivo, evolucionista
evolve verbo	/ɪˈvɑlv/	desarrollar
enzyme sustantivo	/ˈɛn.zaɪm/	enzima
ancestor sustantivo	/ˈæn.sɛs.tɚ/	ancestro, antepasado
trait sustantivo	/tɹeɪt/	rasgo, característica
convergent adjetivo	/kənˈvɜː.d͡ʒənt/	convergente
mammal sustantivo	/ˈmæməl/	mamífero
neuron sustantivo	/ˈn(j)ʊɹɑn/	neurona
phenotype sustantivo	/ˈfiː.nəˌtaɪp/	fenotipo
gradual adjetivo	/ˈɡɹæd͡ʒuəl/	gradual, paulatino
researcher sustantivo	/ˈɹiˌsɝ.t͡ʃɚ/	investigador, investigadora
avian adjetivo	/ˈeɪvi.ən/	aviar, aviano
extracellular adjetivo		extracelular
fertilization sustantivo		fertilización
lineage sustantivo	/ˈlɪn.i.ɪd͡ʒ/	linaje, estirpe

Phrasal verbs que vas a escuchar

Palabra	Significado
figure out verbo	averiguar, captar
find out verbo	averiguar, anoticiarse
pass down verbo	heredar, pasar
turn out verbo	resultar

Gramática en este vídeo

Las estructuras que más usa el hablante, con las palabras exactas del vídeo:

Estructura	En el vídeo
Present perfect continuous have/has been + -ing — una acción que empezó antes y continúa	have been painting · have been fighting
Present perfect have/has + participio pasado — una acción pasada que sigue importando ahora	have set · has changed · has been observed
Voz pasiva be + participio pasado — importa lo que ocurre, no quién lo hace	has been observed · is really needed · should be read
Oraciones de relativo who / which + oración — información extra sobre una persona o cosa	species which are · egg, which are · advantage, which can

Pronunciación a tener en cuenta

El hablante usa 10 contracciones y formas reducidas, como they're, we're, couldn't. Dilas en su forma corta, tal como las oyes.

Los sonidos de “th”: synthesis /ˈsɪnθəsɪs/, mathematical /ˌmæθ(.ə)ˈmæt.ɪ.kəl/
Los sonidos de “sh” y “zh”: evolutionary /ˌiː.vəˈluː.ʃən.ɛɹ.i/, conception /kənˈsɛpʃən/, variation /ˌvɛəɹiˈeɪʃn̩/
Palabras largas — cuida el acento: evolutionary /ˌiː.vəˈluː.ʃən.ɛɹ.i/, equilibrium /ɛkwɪˈlɪbɹɪəm/, reproductive /ˌɹiːpɹəˈdʌktɪv/, accumulate /əˈkjuːmjʊˌleɪt/, biologist /baɪˈɒləd͡ʒɪst/

Cómo practicar con este vídeo

Escucha el vídeo entero una vez sin hablar y anota las palabras que no conoces.
Empieza a velocidad 0,75×, haz shadowing frase por frase y vuelve a la velocidad normal cuando te resulte fácil.
Grábate y compara con el original, prestando atención a palabras como evolutionary, evolve, enzyme.

¿Qué es la Técnica de Shadowing?

Shadowing es una técnica de aprendizaje de idiomas respaldada por la ciencia, desarrollada originalmente para la formación de intérpretes profesionales y popularizada por el políglota Dr. Alexander Arguelles. El método es simple pero poderoso: escuchas audio en inglés nativo y lo repites en voz alta de inmediato, como una sombra que sigue al hablante con solo 1-2 segundos de retraso. A diferencia de la escucha pasiva o los ejercicios de gramática, el shadowing obliga a tu cerebro y músculos de la boca a procesar y reproducir simultáneamente patrones de habla reales. Las investigaciones muestran que mejora significativamente la precisión de la pronunciación, la entonación, el ritmo, el habla conectada, la comprensión auditiva y la fluidez al hablar, convirtiéndola en una de las metodologías más efectivas para la preparación del IELTS Speaking y la comunicación en inglés en el mundo real.

Técnica de shadowing: lee la guía completa paso a paso →

Shadowing Practice: Biggest Breakthroughs in Biology and Neuroscience: 2025 - Learn English Speaking with Video

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