Category Archives: Behavior

Modern Humans: Were We Really Better than Neanderthals, or Did We Just Get Lucky?

Posted on by

OLYMPUS DIGITAL CAMERA

We’ve all heard the story: dim-witted Neanderthals couldn’t quite keep up with our intelligent modern human ancestors, leading to their eventual downfall and disappearance from the world we know now. Apparently they needed more brain space for their eyes. The authors of a recent PLOS ONE paper are digging into the ideas behind this perception, and take a closer look at eleven common hypotheses for the demise of the Neanderthals, comparing each to the latest research in this field to convince us that Neanderthals weren’t the simpletons we’ve made them out to be.

The authors tackled ideas like the Neanderthal’s capacity for language and innovative ability, both often described as possible weaknesses leading to their decline. Analyzing the published research on each topic, they found that archaeologists often used their finds to “build scenarios” that agreed with the running theories of human superiority, and that some long-held truths have now been challenged by recent discoveries and ongoing research at the same excavation sites.

As one example, researchers who found shell beads and pieces of ochre and manganese in South Africa—­used as pigments—claimed them as evidence of the use of structured language in anatomically modern humans. While we can only guess when linking items like these to the presence of language, new findings at Neanderthal sites indicate that they also decorated objects with paints and created personal ornaments using feathers and claws. Whatever the anatomically modern humans were doing in South Africa, Neanderthals were also doing in Europe around the same time, negating the claim that this ability may have provided the anatomically modern humans with better survival prospects once they arrived in Europe.

Another set of South African artifacts led the archaeological community to believe that anatomically modern humans were capable of rapidly improving on their own technology, keeping them ahead of their Neanderthal contemporaries. Two generations of tools, created during the Stillbay and Howiesons Poort periods, were originally believed to have evolved in phases shorter than 10,000 years—a drop in the bucket compared to the Neanderthals’ use of certain tools, unchanged, for 200,000 years. However, new findings suggest that the Stillbay and Howiesons Poort periods lasted much longer than previously thought, meaning that the anatomically modern humans may not have been the great visionaries we had assumed. Additionally, while Neanderthals were not thought capable of crafting the adhesives used by anatomically modern humans to assemble weapons and tools, it is now known that they did, purifying plant resin through an intricate distillation process.

We’re all living proof that anatomically modern humans survived in the end. Perhaps in an effort to flatter our predecessors, we have been holding on to dated hypotheses and ignoring recent evidence showing that Neanderthals were capable of a lot more (and perhaps the anatomically modern humans of a lot less) skill-wise than previously believed. Genetic studies continue to support the idea that anatomically modern humans and Neanderthals interbred and show that the genome of modern humans with Asian or European ancestry contains nearly 2% Neanderthal genes, a substantial quantity considering 40,000 years and 2000 generations have passed since they ceased to exist. These genes may have helped modern humans adjust to life outside of Africa, possibly aiding in the development of our immune system and variation in skin color. Researchers believe that the concentration of Neanderthal genes in modern humans was once much higher, but genetic patterns in modern humans show that hybrid Neanderthal-Human males may have been sterile, leaving no opportunity for their genes to be passed to the next generation.

So, while they may not walk among us today, we have Neanderthals to thank for some major adaptations that allowed us to thrive and spread across the planet. Too bad they’re not here to see the wonderful things we were able to accomplish with their help.

Related links:

Picked Clean: Neanderthals’ Use of Toothpicks to Fight Toothache

Contextualizing the Hobbits

Sharing was Caring for Ancient Humans and Their Prehistoric Pups

Citation: Villa P, Roebroeks W (2014) Neandertal Demise: An Archaeological Analysis of the Modern Human Superiority Complex. PLoS ONE 9(4): e96424. doi:10.1371/journal.pone.0096424

Image 1: Neandertaler im Museum from Wikimedia Commons

The post Modern Humans: Were We Really Better than Neanderthals, or Did We Just Get Lucky? appeared first on EveryONE.

Beating the Odds: Are Goats Better Gamers than Sheep?

Posted on by

goats

We’re all familiar with the shell game, though many may not recognize it by that name. Popular with street swindlers and sports fans at halftime, it has been annoying those unable to locate which cup the ball is under—most people—as long as anyone can remember. But, what if you were a small ruminant playing a modified version of the game, in which cups were not moved? Seems easier, right? Turns out it may depend on what kind of ruminant you are.

The authors of a recent PLOS ONE article updated this age-old game to find out whether goats and sheep, given information upfront about which cup the food was (or was not) under, could find the food again once the cups were replaced. The ability to connect an experience with an imagined result (“If I see that the cup is empty, the other must have the food!”) is called inferential reasoning, and has been tested in dogs, primates, and birds. Different levels of inferential reasoning, especially between two closely related species, may be linked to differences in the way they search for and find food. A deeper understanding of the different feeding behaviors found in ruminants could shed light on the evolutionary practices that shape these behaviors and help us understand how domesticated breeds have modified their behavior over time to better fit a farming environment.

In this study, researchers ran two rounds of testing with slightly different protocols to evaluate how the ruminants’ behavior would change in response to varied amounts of information. They created an experimental set with the animal separated by a series of bars from the researcher and a table (see image above) that held two cups, one with a piece of food hidden underneath. In the first test, researchers lifted one of the following:

  • both cups (full information)
  • the baited cup (direct information – shown in the video below)
  • the unbaited cup (indirect information)
  • no cups (no information)

The animal then chose a cup and was rewarded with food if found. The video below shows a sheep correctly identifying the baited cup after receiving direct information on the food’s location.

To minimize the possibility that animals would simply select the cup most recently moved by the researcher, the authors further modified the game for the second round of testing. A set of internal cups was added under each external cup, some transparent and some opaque, allowing the researchers to lift both external cups simultaneously while providing the same amount of information to the animals.

Animals participating in the test were again presented with two cups. Both external cups were removed simultaneously to reveal the inner set, which were one of the following:

  • both transparent (full information)
  • the baited cup transparent and the unbaited one opaque (direct information)
  • the baited cup opaque and the unbaited transparent (indirect information)
  • both opaque (no information)

In the same way as in the first experiment, animals were given a chance to select a cup and were rewarded with food if found.

When reviewing the results of all the sessions, the authors found that goats were more successful than sheep at identifying the baited cup when given full or direct information, although sheep also chose the baited cup more often under these circumstances. The second experiment showed that goats were also more successful at finding food when provided with indirect information. In both experiments, sheep did not guess better than chance when shown the empty contents of the unbaited cup or no cups at all, and goats did not guess better than chance when neither of the cups were listed.

Though several factors varied between species populations used in this experiment—like the time of day experiments were completed, number of animals tested, or history of testing experience in goats—the authors saw no sign of improved performance due to learning in goats, and no differences in motivation as tests continued.

The researchers speculate that the different foraging behaviors used by goats and sheep allowed goats to get ahead in these experiments. Goats are dietary browsers, meaning they are more selective in what they eat and prefer low-fiber foods, like plant stems and leaves. Sheep, as dietary grazers, feed primarily on high fiber foods like grass, and are not at all particular about what they consume. If goats have evolved to be picky, selective eaters, then it makes sense that they might have a better memory for where they saw food in the past, and the insight to avoid an empty cup when they saw one. Future studies on this topic could provide insight on decision making and risk sensitivity in these animals, and give us a glimpse into the minds of a species that can actually beat the odds in the shell game.

Related links:

Citation: Nawroth C, von Borell E, Langbein J (2014) Exclusion Performance in Dwarf Goats (Capra aegagrus hircus) and Sheep (Ovis orientalis aries). PLoS ONE 9(4): e93534. doi:10.1371/journal.pone.0093534

Image: Figure 1 from article
Video: Video S3 from article

The post Beating the Odds: Are Goats Better Gamers than Sheep? appeared first on EveryONE.

Squirrels – Nut Sleuths or Just Nuts?

Posted on by

squirrel2

Crazed squirrels: we’ve all seen them. Some dashing toward you only to stop short long enough to glare with beady eyes before fleeing, others dive-bombing the dirt, coming up with their heads waving back and forth. They’re the butt of many a joke on college campuses, providing endless amusement with their antics. Some UC Berkeley students even think that the resident campus squirrels may have gobbled up substances left over from the wilder moments of Berkeley’s past, leaving them permanently crazed. However, according to a recently published PLOS ONE article from UC Berkeley, these squirrels’ seemingly odd behavior may actually have a purpose. We’ve long known that scatter-hoarders will store food they find to prepare for periods when it’s less abundant, but there is little information on the hoarding process. Turns out these squirrels might actually have a refined evaluation method based on economic variables like food availability and season. To eat now, or cache for later?

Researchers interacted with 23 fox squirrels, a species well-habituated to humans, in two sessions during the summer and fall of 2010 on the Berkeley campus, evaluating food collection behavior during both lean (summer) and bountiful (fall) seasons. The authors engaged the squirrels with calls and gestures to attract their attention, and the first squirrel to approach was the focus of that round of testing.

Each squirrel was given a series of 15 nuts, either peanuts or hazelnuts, in one of two sequences. Some were offered five peanuts, followed by five hazelnuts, then five more peanuts (PHP). Others were given five hazelnuts, five peanuts, then five hazelnuts (HPH). The purpose of this variation was to evaluate how squirrels would respond to offers of nuts with different nutritional and “economic” values at different times. Hazelnuts are, on average, larger than peanuts, and their hard shell prevents spoiling when stored long term, but peanuts tend to have more calories and protein per nut.  Researchers videotaped and coded each encounter to calculate variables, like the number of head flicks per nut, time spent pawing a nut, and time spent traveling or caching nuts. See the video below for a visual example of these behaviors.

https://www.youtube.com/watch?v=MKKgpZoZ0Y0&feature=youtu.be

The results showed that season and nut type significantly affected the squirrel’s response, and the squirrel’s evaluation of the nut could forecast its course of action. Predictably, the fall trial showed squirrels quickly caching most of their nuts, likely taking advantage of the season’s abundance. Squirrels ate more nuts in the summer, though they still cached the majority of hazelnuts (76% vs. 99% cached in the fall) likely due to their longer “shelf life”.

The squirrels who head-flicked at least one time in response to a nut cached it nearly 70% of the time, while those who spent more time pawing the nut tended to eat it (perhaps searching for the perfect point of entry?). The time spent caching and likelihood of head flicking were clearly linked to the type of nut received and to the trial number, with time spent evaluating a nut decreasing as the trials continued for a squirrel. The authors suggest that the changes in food assessment strategies in response to resource availability provide an example of flexible economic decision making in a nonhuman species.

So, now that squirrels are possibly making economically prudent decisions when evaluating nuts, I guess we have to give them a break when we see them running around like crazy on campus. Doesn’t mean we’ll stop laughing.

Citation: Delgado MM, Nicholas M, Petrie DJ, Jacobs LF (2014) Fox Squirrels Match Food Assessment and Cache Effort to Value and Scarcity. PLoS ONE 9(3):e92892. doi:10.1371/journal.pone.0092892

Image: Squirrel by likeaduck

Video: Video S1 from the article

The post Squirrels – Nut Sleuths or Just Nuts? appeared first on EveryONE.

Mama Gorilla Knows Best

Posted on by

gorilla

While few question the importance of maternal care in humans, scientists do question the influence of a mother’s behavior in other species. Researchers from the Max Planck Institute for Ornithology have now published an article in PLOS ONE showing exactly how important a mother’s guidance can be to our friend the western lowland gorilla. After monitoring the spread of two specific behaviors in captive groups of gorillas, the authors suggest that gorilla mothers play a vital role in social learning and the transmission of behaviors between generations.

The authors videotaped gorilla behavior for 4-6 hours per day over the course of eight weeks in 2000 and 2010 at Howletts Wild Animal Parks. Throughout their sittings, they watched for two specific behaviors shown by different individuals: the “Puff-Blowing” technique, used during mealtimes to separate oat from chaff, and the “Throw-Kiss-Display,” one male gorilla’s coy way of drawing visitors’ attention to him. Check out the live-action versions in the videos below.


During the initial observational period in 2000, the “Puff-Blowing” technique was used by three adult females, while the “Throw-Kiss-Display” was implemented by a single silverback male, Kouillou, and no other members of the group.

By the time the researchers returned in 2010, the “Puff-Blowing” technique was practiced by 15 individuals, while the “Throw-Kiss-Display” had been dropped entirely, even by the original practitioner.

When the researchers analyzed the data, they found that the spread of the observed “Puff-Blowing” technique to new gorillas could be tracked through mother-child relationships. All but three offspring (13 total) of the original three mothers used the technique. Furthermore, this behavior was never seen in the offspring of mothers who did not perform the technique.

Based on their observations, the authors suggest that the actions of the gorilla mother play a major role in the transmission of behaviors. In other words, baby gorilla see, baby gorilla do. While the authors mention that “Puff-Blowing” may be more likely to be passed down because it’s useful at mealtime—unlike the “Throw-Kiss-Display”—they argue that the path of transmission (mother-offspring) is significant. The authors also indicate that genetic factors may affect the occurrence of these behaviors, as not all offspring of the “Puff-Blowing” mothers inherited the action, suggesting that other forces may be at play.

Lesson learned: Even gorillas need their mommies.

For more evidence of the importance of mothers in the animal kingdom, check out this paper on migration patterns in humpback whales.

Citation: Luef EM, Pika S (2013) Gorilla Mothers Also Matter! New Insights on Social Transmission in Gorillas (Gorilla gorilla gorilla) in Captivity. PLoS ONE 8(11): e79600. doi:10.1371/journal.pone.0079600

Image Credit: USINFO Photo Gallery

Videos: S1 and S2 from the paper

 

I’ll Have What He’s Having: Dogs Eavesdrop on Human Interactions

Posted on by

dogs_begging

In the spirit of Thanksgiving and sharing a warm meal with loved ones, we’d like to take a moment to give some social credit to our loving, faithful, and clever furry friends. Researchers have been investigating the question of whether animals can eavesdrop—or listen in on third-party interactions—for some time, and evidence of potential eavesdropping has been identified in dogs and other mammals, fish, and birds.

Dogs are especially good candidates for studying eavesdropping because they are social animals and have been domesticated, so they are accustomed to interacting with humans day-in and day-out. Most dog owners know how well their dogs can “read” them, and some might argue that their dogs can do this better than other people they know. Researchers have also confirmed that dogs can recognize human emotions, facial expressions, and friendliness versus hostility, the latter even in strangers.

In a more nuanced form of social interaction, dogs have been shown to prefer certain people over others depending on the outcome of third-party interactions. To further investigate how dogs respond to interactions among people, the authors of this recently published PLOS ONE article asked whether dogs can develop a preference for or against givers, or “donors,” in a “begging” interaction between people.

journal.pone.0079198.g001-1

The study recruited 72 dogs of various breeds and sizes and put them in a testing environment that either resembled a home or a dog care facility. While the dog watched from across the room, two human assistants acted as “donors” (females, pictured above) who offered food to a “beggar” (male, above), and the beggar either reacted positively or negatively to the offered food. The extent of the reaction was controlled to try to determine which social cues the dog was picking up on: gesture + verbal (GV), gesture only (G), or verbal (V) only.

In the GV group positive scenario, the beggar received a yummy corn flake, ate it, and said “So tasty!”; in the negative scenario, the beggar said “So ugly!” gave the corn flake back, and then turned his back. The G and V groups differed in that they isolated the gesture and verbal components, respectively. After the beggar left, the dog was released and had 10 seconds to decide between the donors, who did not signal the dog in any way. Dogs that did not make a choice were removed from the analysis.

As the results below show, dogs were more likely to choose the donor who received a positive reaction; the authors also noted that the dogs tended to watch or gaze at the donor who received a positive reaction longer than the donor who received a negative reaction. However, the authors state that both gesture and verbal cues (the GV group) were required to show a reliable difference among the groups.

journal.pone.0079198.g002

Although these results alone are not conclusive, as it is difficult to control for all the variables affecting these scenarios (e.g., the authors note that dogs chose randomly if the donors switched places), the authors suggest that the dogs may have attributed a “reputation” to the donor based on the beggar’s reaction, where both gesture and verbal cues were required for the dog to make this association.

While not the same as a scientific experiment, it might be fun to “test” your dog in various eavesdropping scenarios, especially in relation to available food* on the Thanksgiving table.

Happy Thanksgiving from PLOS ONE!

Citation: Freidin E, Putrino N, D’Orazio M, Bentosela M (2013) Dogs’ Eavesdropping from People’s Reactions in Third Party Interactions. PLoS ONE 8(11): e79198. doi:10.1371/journal.pone.0079198

Image Credits: Figure 1 by carterse, Figures 2 and 3 from the article

*food safe for pets to eat, of course!

Picked Clean: Neanderthals’ Use of Toothpicks to Fight Toothache

Posted on by

Toothpick1

The toothpick —an often unnoticed tool for post-meal rituals and appetizer stability—has played a greater role in our ancestors’ health and comfort than many would imagine. In a world before dentists, Neanderthals and modern humans took oral hygiene into their own hands using the only tools they had readily available: little bits of nature they found surrounding them.

Researchers from Spain have presented evidence in PLOS ONE that Neanderthals used small sticks or blades of grass not only to remove fragments of food from between their teeth, but also to lessen the pain caused by periodontal disease, a form of gum disease. While multiple human and Neanderthal remains have been found showing evidence of toothpick use, the authors propose that the combined evidence of toothpick use and gum disease suggests that Neanderthals were perhaps practicing an early form of dental care.

The samples in the image above show an adult’s upper jaw with three teeth left intact found at the Cova Foradà cave site in Valencia, Spain, amidst animal remains and tools dated to the Mousterian era (300,000-30,000 years ago). The adult teeth, believed to belong to an individual between 35-45 years old, show heavy wear on the top surface and exposed roots, the result of a lifetime’s consumption of fibrous and abrasive foods like meats and grains. There are no signs of cavities in the remaining teeth, though decayed bone and the porous surface texture of the left side of the jaw indicate the presence of gum disease.

Two distinct grooves are present on the sides of the existing premolar and molar above the crown of the tooth. These grooves were caused by consistent dragging of a tool across the side of the tooth. The existence of these marks above the gum line indicates heavy dental wear and disease. Here, the gums had receded and left the base of the tooth unprotected. With the roots exposed, it would be easy for leftover debris from meals to get stuck and put pressure on already inflamed gums. The use of a foreign object pushed between the teeth would remove any particles lodged in this sensitive area. Without the extra burden of invasive food detritus, force on the gums would be reduced and irritation and pain would decrease.

Over the last few years, studies have shown that Neanderthals were capable of complex behaviors and emotions, may have used a sophisticated language, were more often right-handed than left, and were generally not the inferior cousins some thought they were. As this study shows, they practiced dental care as well. So, the next time you’re heading out of your favorite restaurant, take a good look at that bowl of toothpicks at the front: the contents could very well be evidence of one of our oldest habits.

Check out more coverage of this article in National Geographic and Archaeology magazine.

Citation: Lozano M, Subirà ME, Aparicio J, Lorenzo C, Gómez-Merino G (2013) Toothpicking and Periodontal Disease in a Neanderthal Specimen from Cova Foradà Site (Valencia, Spain). PLOS ONE 8(10): e76852. doi:10.1371/journal.pone.0076852

Image Credit: Image from Figure 2 of the manuscript