Scientists have demonstrated that the South American tiger cat complex Leopardus tigrinus consists of five genetically distinct species, including one entirely new to science.
The Leopardus tigrinus species complex is a group of small, spotted felines found across Central and South America and known variously as tiger cats, little spotted cats, or tigrinas.
Their subtle physical differences have made them notoriously difficult to classify, and previous efforts relying on limited morphological and mitochondrial DNA data produced contradictory conclusions.
“Much of the Earth’s biodiversity remains unknown, which poses a challenge to conservation planning in the face of rampant anthropogenic impacts,” said Dr. Jonas Lescroart, a researcher at the University of Antwerp and the Pontifical Catholic University of Rio Grande do Sul, and his colleagues.
“A necessary step for biodiversity assessments is to correctly delimit species.”
“In this context, species complexes, due to their subtle boundaries, present a serious challenge to straightforward taxonomic assignment.”
“The tiger cat species complex presents one such example, having eluded taxonomic resolution since the description of its nominal species, Leopardus tigrinus, based on a single illustration of an animal from Cayenne, French Guiana.”
To resolve the puzzle, the authors analyzed complete genomes from 38 individuals across the genus Leopardus.
The Leopardus tigrinus species complex is a group of small, spotted felines found across Central and South America and known variously as tiger cats, little spotted cats, or tigrinas.
Their subtle physical differences have made them notoriously difficult to classify, and previous efforts relying on limited morphological and mitochondrial DNA data produced contradictory conclusions.
“Much of the Earth’s biodiversity remains unknown, which poses a challenge to conservation planning in the face of rampant anthropogenic impacts,” said Dr. Jonas Lescroart, a researcher at the University of Antwerp and the Pontifical Catholic University of Rio Grande do Sul, and his colleagues.
“A necessary step for biodiversity assessments is to correctly delimit species.”
“In this context, species complexes, due to their subtle boundaries, present a serious challenge to straightforward taxonomic assignment.”
“The tiger cat species complex presents one such example, having eluded taxonomic resolution since the description of its nominal species, Leopardus tigrinus, based on a single illustration of an animal from Cayenne, French Guiana.”
To resolve the puzzle, the authors analyzed complete genomes from 38 individuals across the genus Leopardus.
They sequenced DNA from eight historical museum specimens, including skull fragments from Guyana that provided the first-ever genetic data from the species’ original type locality in the Guiana Shield, a population that had never before been molecularly sampled.
The genomic analysis confirmed five reciprocally distinct lineages within the complex, alongside the previously recognized southern tiger cat (Leopardus guttulus).
Among the findings was a previously unknown species, named Leopardus tilcayo, discovered in Bolivia’s Yungas cloud forests.
The researchers also identified a new subspecies from Peru’s Yungas region, Leopardus tigrinus antisuyo.
“Leopardus tilcayo is a small felid with a head-body length of 42.5-50.5 cm (17-20 inches) and a tail length of 25-26.5 cm (10-10.4 inches),” they said.
“It has a light brown dorsum, darker along the mid-dorsal ridge and paler toward the limbs.”
“The pelage is characterized by relatively large, irregular, dark brown to black rosettes, mostly open or partially closed, on a light brown to beige background.”
“Leopardus tilcayo diverged from the Leopardus tigrinus/pardinoides lineage nearly 1.4 million years ago, during the Early Pleistocene period,” they added.
“This period was marked by substantially fluctuating climatic conditions that led to the fragmentation of the montane forest, which likely facilitated geographic isolation.”
Beyond taxonomy, the new genomic data revealed a long-term population decline across nearly all tiger cat units dating back through the Pleistocene and Holocene epochs, with some lineages — including the newly described Leopardus tilcayo — showing population decreases of 60% or more.
“Altogether, our results clarify the evolutionary history of a complex radiation of wild cats, reveal novel taxa, and serve as a basis for conservation planning on behalf of these elusive wild cats,” the scientists concluded.
The discovery is described in a paper in the journal Current Biology.
Jonas Lescroart et al. Phylogenomics and museomics reveal five distinct species of tiger cats in South America. Current Biology, published online September 17, 2026; doi: 10.1016/j.cub.2026.08.059
Timeline of the universe, from Big Bang to present day. The far left depicts the earliest moment we can probe so far, when a period of cosmic inflation produced a burst of exponential growth in the universe. For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate the expansion of the universe. Read more about this image from NASA.
You’ve probably heard of the Big Bang as the event that gave rise to our universe. You might know most cosmologists believe it occurred some 13.8 billion years ago. It’s hard to fathom that, at the moment of the Big Bang, all of the energy in the universe – some of which would later become galaxies, stars, planets and human beings – was concentrated into a tiny point, smaller than the nucleus of an atom. And it’s not just matter that was born in the Big Bang. In the view of modern cosmologists, matter and space and time all began when that microscopic point suddenly expanded violently and exponentially.
The first atoms are thought to have formed when the universe was around 400,000 years old. Before that, the universe was simply too hot and too energetic to let atomic nuclei capture electrons. The first stars sparkled into life, cosmologists believe, about 250 million years after the Big Bang, and the first galaxies shortly after that.
The Hubble Space Telescope captured this image of an exceedingly distant galaxy called UDFj-39546284. This object has a redshift of z~10, meaning that it existed some 480 million years after the Big Bang. Image via NASA/ ESA/ Garth Illingworth/ Rychard Bouwens/ the HUDF09 Team/ Wikimedia Commons.
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Here’s another exceedingly distant (and therefore old) object, captured by the Hubble Space Telescope in 2016. Galaxy GN-z11, shown in the inset, is seen as it was 13.4 billion years in the past, just 400 million years after the Big Bang, when the universe was only 3% of its current age. The galaxy is ablaze with bright, young, blue stars, but looks red in this image because its light has been stretched to longer spectral wavelengths by the expansion of the universe. Image via NASA/ ESA/ P. Oesch/ G. Brammer/ P. van Dokkum / G. Illingworth/ Hubblesite.
Big Bang is a theory
The Big Bang refers to a theory. How could it be otherwise? The current version of Big Bang theory – the one used most by modern cosmologists – is called the Lambda-CDM model. It postulates that our universe began at a specific instant, expanded to be flat (i.e. has zero curvature) and is made up of 5% baryons (i.e. the matter that makes up everything we see – galaxies, stars, planets, people), 27% cold dark matter (hence the “CDM” of the theory’s name) and 68% dark energy.
The Lambda-CDM model further states that the universe is expanding at a rate referred to as Lambda (the Greek letter) and is governed by the principles of Einstein’s General Relativity. The Lambda-CDM model has been spectacularly successful at explaining what we observe in the universe. It makes predictions repeatedly confirmed by observation. But it is not without problems; as with all scientific theories, the Lambda-CDM model continues to evolve.
Now let’s pause a moment, so that we might draw a distinction between the appearance of all that energy in the Big Bang and its sudden expansion. In that sense, the Big Bang was not the event that caused our universe. Rather, it was the event that gave birth to the universe. Why is this distinction important? It’s important because, although science has been able to establish a history of the universe right back to when that tiny point suddenly created our entire cosmos, what preceded it, the reason for that tiny point of energy being there in the first place, is unknown, and may forever be unknowable.
The unanswerable question
The Big Bang is the theory we have constructed for how the universe we see around us came to be. It does not attempt to answer the most common question we humans ask about the origin of the cosmos: why? And this question likely cannot be answered, because, by definition, whatever caused the appearance of that tiny point of energy, containing the seeds of everything that would ever be, was not of this universe.
Therefore, whatever caused the universe left no evidence of its existence for us to study, no clue as to what it was. It is also likely that, being something completely outside the universe, we would, in any event, be unable to comprehend it. The laws of physics, of motion, of gravity, of electromagnetism, of thermodynamics, simply did not apply at the moment of the universe’s birth because they did not yet exist: they certainly cannot describe the presence and origin of that tiny seed.
No answer
That has not stopped cosmologists, who study the history and large-scale structure of the universe, from trying to answer such questions, of course, because that’s the nature of science. Some people attribute the existence of that tiny seed of energy to a god, as humans have invented gods throughout the ages to explain things they could not understand, but there is absolutely no reason for believing that idea, other than perhaps wishful thinking. There is certainly nothing we observe in the history of the universe to suggest that its origin was anything other than a natural event, even if we cannot comprehend it. On the other hand, there’s nothing to suggest the origin of our universe was not caused by a god, either.
Artist’s representation of the history of the universe and the arrow of time. Big Bang theory implies that time moves in a single direction. However, scientists have discovered that, at the quantum level, in the realm of sub-atomic particles, many processes are what we call “time-reversible”: there is no distinction between past, present and future. Image via Forbes.
Time started with the Big Bang
The Lambda-CDM model also states that time itself started at the Big Bang, on the basis that if there are no events, there is no time to measure. This raises an old philosophical question of whether time is a human construct or exists independently of us. This question has taxed some of the greatest philosophers and scientists but has never been answered satisfactorily. Still, if we define time as the period which elapses between events, it is fair to say that time started with the Big Bang.
Another common question is: what happened before the Big Bang? That question can have no meaning if we accept the Big Bang was the start of the universe’s clock: it’s like asking what’s north of the North Pole. This answer, while demonstrating the irrationality of asking about a “before”, is not, however, satisfactory to humans accustomed to cause and effect: we reason that if the Big Bang was an event which was the result of something, some change, some instability, there had to be a before.
However, that is only in our experience, in the world we are familiar with, where an event always has a cause, and has absolutely no bearing on the universe coming into being because, again, the laws of physics, which in our world govern cause and effect, simply did not exist. And as if to underline how superficial, how biased, our perception of time, scientists have discovered that at the quantum level, in the realm of sub-atomic particles, many processes are what we call “time-reversible:” there is simply no distinction between past, present and future.
Space began at the Big Bang
It’s also important to realize that, at the moment of the Big Bang, there was no space and there were no dimensions. Space itself, and the dimensions within that space, came into being at that moment, as the bubble of energy expanded. This means that, contrary to what most people believe, the Big Bang was not an explosion. Think of anything exploding, and it explodes into a space, an area, which was there already. But in the case of the Big Bang, there was no preexisting space for an explosion to occur in.
A related question which is often asked is: where did the Big Bang happen? Those who ask this believe you can point at a location in the sky and say, “it happened there.” But the answer to the question is that the Big Bang happened everywhere. It’s just that everywhere existed within that tiny bubble of infinitely-hot expanding energy, because there was literally nothing outside it – no space, no dimensions, nothing. Watch any documentary about the Big Bang and it will show it as a huge explosion, viewed from outside. But such a viewpoint is impossible – there was no “outside”. One cannot, of course, blame filmmakers for this: there is simply no way to portray the Big Bang visually in a way which is scientifically accurate. It’s doubtful we even have the vocabulary to describe it, let alone portray it.
Space itself is believed to have been born in the Big Bang. Artist’s concept via Christine Daniloff/ MIT/ ESA/ Hubble/ NASA/ Phys.org.
Alternative theories?
If you find it difficult to get your head around the idea of the Big Bang happening everywhere, with no outside, at a particular moment when time started some 13.8 billion years ago, you are not alone. The human brain is not well equipped for dealing with such concepts. Even when Edwin Hubble, in the 1920s, demonstrated that the universe is expanding in all directions, and therefore, if you wind the clock back far enough, all of the universe must have occupied one tiny point, the idea that the universe had a definite beginning, and was therefore not infinitely old, was simply unacceptable to many.
Among these who rejected the Big Bang were prominent scientists: Einstein himself denied the idea of an expanding universe. Another scientist who rejected the notion of a universe of finite age was famed British astronomer Sir Fred Hoyle, the man who, more than any other individual, unlocked the mystery of how stars work.
Hoyle gave a series of lectures on BBC radio in the late 1940s and early ’50s, and, on one of these – on the BBC’s Third Programme broadcast on March 28, 1949 – he poured derision on the idea of the universe beginning at a fixed point in time and referred to cosmologists’ description of the event as a “Big Bang.” Unfortunately for Hoyle, the name stuck, and we’ve called this event the Big Bang ever since.
Fred Hoyle. He coined the term “Big Bang” to describe the event in which our universe was born, while explaining a rival theory, the Steady State theory, in a radio talk in 1949 Image via Britannica.com.Image via ExploringCosmos006.
Hoyle’s rejection of the Big Bang theory
Hoyle never accepted that the universe had a beginning, even until his death at the age at 86 in 2001. He became the leading proponent of Steady State Theory, which says that the universe has no beginning or end: it constantly regenerates itself, with new matter condensing out of nothing.
Hoyle’s blunt intransigence – he was from Yorkshire, an English county said to be famed for the plain-speaking and directness of its inhabitants – was not lessened by the subsequent success of Big Bang theory, not even after it successfully predicted the abundancies of light elements, such as hydrogen, helium and lithium, in the universe.
Nor did he come to accept the Big Bang when Arno Penzias and Robert Wilson discovered the predicted Cosmic Microwave Background, the Big Bang’s dying echo, in 1964. Steady State Theory had predicted none of these things, nor did it have explanations for them.
It just wouldn’t work
Nor was Hoyle fazed when Alan Guth constructed the theory of Cosmological Inflation as a refinement to existing Big Bang theory in 1979. Inflation explains why the universe is the same temperature everywhere and is “flat”, amongst other features of the universe not hitherto explained, although it has yet to be observationally completely verified.
Even the year before he died, Hoyle published yet another scientific paper on Steady State theory, but by this time his ideas were completely rejected by most cosmologists. And, sadly for him, they were also rejected by the overwhelming observational evidence for the Big Bang. Steady State Theory just does not work, makes false predictions and is contradicted by what we actually see in the universe. As a hypothesis – lacking supporting observational evidence, it was that rather than a theory, although commonly referred to as such – it essentially died with Hoyle.
Today’s Big Bang model
Today, the Lambda-CDM Big Bang model is the only theory that makes any testable predictions and that is supported by observations.
Most cosmologists today believe we know the history of the universe back to 10-21 seconds after the Big Bang – that’s 0.0000000000000000000001 seconds. The painstaking piecing together of this history over the last 50 years, although lacking in fine detail as it undoubtedly is, represents humans’ greatest intellectual achievement, our species’ crowning glory. It has been achieved through an unparalleled synthesis of astronomy, astrophysics, cosmology, particle physics, chemistry and other sciences.
But science will not rest until we can push our theories back even further in time, to that exact moment when the universe came into being.
Artist’s concept of the Big Bang, the event now believed to have marked our universe’s birth. If we looked far enough back in time, could we witness the birth of the universe?
Bottom line: At the moment of the Big Bang, all of the energy in the universe – some of which would later become galaxies, stars, planets and human beings – was concentrated into a tiny point, smaller than the nucleus of an atom. And it’s not just matter that was born in the Big Bang. In the view of modern cosmologists, matter and space and time all began when that microscopic point suddenly expanded violently and exponentially.
Time is certainly a very complex topic in physics, and there are people who believe that time does not actually exist. One common argument they use is that Einstein proved that everything is relative, so time is irrelevant. In the bestselling book "The Secret," the authors write, "Time is just an illusion." Is this really true? Is time just a figment of our imagination?
Among physicists, there is no real doubt that time does really, truly exist. It's a measurable, observable phenomenon. Physicists are just divided a bit on what causes this existence, and what it means to say that it exists. Indeed, this question borders the realm of metaphysics and ontology (the philosophy of existence) as much as it does on the strictly empirical questions about time that physics is well-equipped to address.
The Arrow of Time and Entropy
The phrase "the arrow of time" was coined in 1927 by Sir Arthur Eddington and popularized in his 1928 book "The Nature of the Physical World." Basically, the arrow of time is the idea that time flows in only one direction, as opposed to dimensions of space that have no preferred orientation. Eddington makes three specific points in regards to the arrow of time:
It is vividly recognized by consciousness.
It is equally insisted on by our reasoning faculty, which tells us that a reversal of the arrow would render the external world nonsensical.
It makes no appearance in physical science except in the study of the organization of a number of individuals. Here the arrow indicates the direction of progressive increase of the random element.
Things Decay
The first two points are certainly interesting, but it's the third point that captures the physics of time's arrow. The distinguishing factor of the arrow of time is that it points in the direction of increasing entropy, per the Second Law of Thermodynamics. Things in our universe decay as a course of natural, time-based processes—but they do not spontaneously regain order without a lot of work.
Time Is All Over the Place
There's a deeper level to what Eddington says in point three, however, and that is that "It makes no appearance in physical science except..." What does that mean? Time is all over the place in physics.
While this is certainly true, the curious thing is that the laws of physics are "time reversible," which is to say that the laws themselves look as if they would work perfectly well if the universe were played in reverse. From a physics standpoint, there's no real reason why the arrow of time should by necessity be moving forward.
Entropy Continuously Increases
The most common explanation is that in the very distant past, the universe had a high degree of order (or low entropy). Because of this "boundary condition," the natural laws are such that the entropy is continuously increasing. (This is the basic argument put forth in Sean Carroll's 2010 book "From Eternity to Here: The Quest for the Ultimate Theory of Time," though he goes further to suggest possible explanations for why the universe may have started off with so much order.)
'The Secret' and Time
One common misconception spread by an unclear discussion of the nature of relativity and other physics related to time is that time does not, in fact, exist at all. This comes across in a number of areas that are commonly classified as pseudoscience or even mysticism, but I'd like to address one particular appearance in this article.
In the best-selling self-help book (and video) "The Secret," the authors put forth the notion that physicists have proven that time does not exist. Consider a few of the following lines from section "How Long Does It Take?" in the chapter "How to Use the Secret" from the book:
"Time is just an illusion. Einstein told us that."
"What quantum physicists and Einstein tell us is that everything is happening simultaneously."
"There is no time for the Universe and there is no size for the Universe."
False Statements
All three of the statements above are categorically false, according to most physicists (especially Einstein!). Time is actually an integral part of the universe. As mentioned earlier, the very linear concept of time is tied into the concept of the Second Law of Thermodynamics, which is seen by many physicists as one of the most important laws in all of physics! Without time as a real property of the universe, the Second Law becomes meaningless.
What is true is that Einstein proved, through his theory of relativity, that time by itself was not an absolute quantity. Rather, time and space are united in a very precise way to form space-time, and this space-time is an absolute measure that can be used—again, in a very precise, mathematical way—to determine how different physical processes in different locations interact with each other.
Everything Does Not Happen Simultaneously
This does not mean that everything is happening simultaneously, however. In fact, Einstein firmly believed—based on the evidence of his equations (such as E = mc2)—that no information can travel faster than the speed of light. Every point in space-time is limited in the way it can communicate with other regions of space-time. The idea that everything happens simultaneously is exactly counter to the results that Einstein developed.
This and other physics errors in The Secret are perfectly understandable because the fact is these are very complex topics, and they are not necessarily completely understood by physicists. However, just because physicists don't necessarily have a complete understanding of a concept such as time does not mean that it's valid to say they have no understanding of time, or that they've written off the whole concept as unreal. They most assuredly have not.
Transforming Time
Another complication in the understanding of time is demonstrated by Lee Smolin's 2013 book "Time Reborn: From the Crisis in Physics to the Future of the Universe," in which he argues that science does (as the mystics claim) treat time as an illusion. Instead, he thinks that we should treat time as a fundamentally real quantity and, if we take it seriously as such, we will uncover laws of physics that evolve over time. It remains to be seen if this appeal will actually result in new insights into the foundations of physics.
