Pleistocene footprints show intensive use of lake margin habitats by Homo erectus groups Roach et al., 2016


Figure 1: Photographs of 1.5 Ma tracks recovered near Ileret, Kenya.
Clockwise from upper right: White rhinoceros (Ceratotherium simum), pelican (Pelecanus), hominin (putative Homo erectus), large wading bird (Ciconiidae or Gruidae), elephant (Elephas or Loxodonta) and medium sized bovid. Photos: N. Roach/K. Hatala.

Abstract:
"Reconstructing hominin paleoecology is critical for understanding our ancestors’ diets, social organizations and interactions with other animals. Most paleoecological models lack fine-scale resolution due to fossil hominin scarcity and the time-averaged accumulation of faunal assemblages. Here we present data from 481 fossil tracks from northwestern Kenya, including 97 hominin footprints attributed to Homo erectus. These tracks are found in multiple sedimentary layers spanning approximately 20 thousand years. Taphonomic experiments show that each of these trackways represents minutes to no more than a few days in the lives of the individuals moving across these paleolandscapes. The geology and associated vertebrate fauna place these tracks in a deltaic setting, near a lakeshore bordered by open grasslands. Hominin footprints are disproportionately abundant in this lake margin environment, relative to hominin skeletal fossil frequency in the same deposits. Accounting for preservation bias, this abundance of hominin footprints indicates repeated use of lakeshore habitats by Homo erectus. Clusters of very large prints moving in the same direction further suggest these hominins traversed this lakeshore in multi-male groups. Such reliance on near water environments, and possibly aquatic-linked foods, may have influenced hominin foraging behavior and migratory routes across and out of Africa."

I just thought that it'd be cool to see these two compared

BARROW, Alaska -- Most Alaskans and Canadians have a bear story - tales of fearsome grizzlies, even polar bears. But a mix of the two?
They're known as pizzlies or grolars, and they're a fusion of the Arctic white bear and their brown cousins. It's a blend that's been turning up more and more in parts of Alaska and Western Canada.
Bears sharing both species' DNA have been recorded several times over the past decade. So why are these two species linking up?
It's called flexible mate choice: The bears are mating with the best possible partners as opposed to not mating at all, and they're mating because they share relatively close territories and the same branches of the same evolutionary tree.
Intraspecies mixing between the two happened thousands of years ago, thanks to the advance and retreat of glaciers, and of late, it has been boosted by climate change. Scientists say it's also probably been assisted by policies that protect both bears from culling and hunting, affording further opportunities for mingling.
The crossbreeds found in Alaska and Canada are not genetic anomalies. Scientists have found the mix in the islands off Southeast Alaska, where bears resemble grizzlies but contain polar bear DNA. That indicates decades of sporadic interbreeding, said Steven Amstrup, chief scientist at Polar Bears International.

The polar-grizzly cocktail is also far from the only recent animal hybrid. The coywolf - a coyote-dog-wolf amalgamation - and a lynx-bobcat mix have been popping up along the northern Atlantic coast. The more scientists analyze species' genomes, the more they realize that animals we label as "pure breeds" actually share DNA - and that includes us.

Many humans carry traces of DNA from Neanderthals, which means we're all hybrids. It also means there's no such thing as genetic purity. The concept is a romantic construct, an anthropomorphized take on nature. And what may be most surprising about this, researchers say, is the role interbreeding plays in the futures of endangered species - or, as the case may be with polar bears, accelerating their end.
Amstrup has studied bears in the Arctic since the 1970s and was instrumental in helping list the polar bear as a threatened species in 2008. He, like other experts, characterizes this "new" bear relationship as more beneficial to grizzlies than polar bears. That's because there are more grizzlies than polar bears and because grizzly territory is expanding while polar bear territory is contracting. What that adds up to is a good chance grizzlies could essentially dilute the polar bear population until it doesn't exist at all, they say.
Polar bears are getting the short end of the stick in this relationship, not "gaining any genetic diversity," said Geoff York, who led research on polar bears at the World Wildlife Fund for almost a decade before joining Amstrup at PBI.

Andrew Derocher, a professor of biological studies at the University of Alberta, has spent three decades studying bears throughout the Arctic. He, too, has a sobering view about where the hybridization is heading.



"I hate to say it, but from a genetic perspective, it's quite likely grizzly bears will eat polar bears up, genetically," he told me. And he says the changes are already at play.

All hybrids that have been analyzed had grizzly fathers, because grizzly males roam to establish territory and come in contact with receptive female polar bears. Female grizzlies tend not to stray far from their home ranges, and male polar bears don't usually creep into grizzly habitats.
Polar bears need the ice - that's where the seals and walruses they eat live. They don't hibernate, and they don't travel south of the tundra. Grizzlies, historically, rarely ventured north of the treeline. Permafrost is too cold for their liking, and they sink into the snow easily. (Polar bears have padded paws that act as snowshoes). Hunting is more challenging in the north, where prey is scarce. They're not really swimmers. 
But shifts are afoot.

"What we're starting to see in the Canadian Arctic is three-fourth grizzlies," Derocher said, referring to the offspring of 50-50 hybrids that then mated with grizzlies. "How do they act? Probably more like grizzly bears, living on land. As climate change continues, terrestrial habitat is going to increase, and the likelihood is the habitat for grizzlies, a terrestrial bear, is going to get better. That means a longer warming period and greater food potential."

Derocher said it will not be long before we start seeing female grizzlies bump into male polar bears, further straining the polar bear's genetic variation. "I suspect at the same time that that's occurring, we'll start to see polar bears on their way out."

When will that be? Impossible to say, but some experts think that as the Arctic continues warming, it may be only a few decades, perhaps a century. There are about 20,000 to 25,000 polar bears in the Circumpolar Arctic, and "an order of magnitude higher for grizzlies in that area" and other brown bears, Derocher said. "It shouldn't be a big surprise that grizzlies are moving north - everything is."
Right now, polar bears are also threatened by polychlorinated biphenyls, or PCBs, and other toxic pollution - primarily from eating seals and other animals affected by these carcinogens - that has been linked to brain damage, even causing some bears' baculums, or penis bones, to break off. 
And those outcomes could affect polar-grizzly hybrids as badly as pure breeds. No matter what bear ends up as the Arctic's future apex predator, scientists say, if the issues up north aren't solved, it won't matter what bears are there.

Hybrids are "a normal part of the evolutionary process," Derocher said. But if the ice disappears, "we won't have grizzlies or polar bears in this area. If you roll the clock ahead another number of decades or a century, quite clearly it's going to be no bears eventually." 
                                  

*This image is copyright of its original author

http://www.adn.com/wildlife/2016/5/23/lo...ow-mating/

(05-22-2016, 01:23 AM)Pckts Wrote: I'd hate to believe that the best chance of saving lions or any species would be killing them....any one of them.
I don't buy into the fact that hunting will generate massive contributions for conservation and in turn, it's a good thing. Killing and Conservation are contradicting things, Eco-tourism generates massive revenues, the money needs to be distributed far better before we declare "monitored hunting" a secret weapon in the protection of an apex predator.
I find it sad that somebody like Packer feels that way, I think it shows just how hopeless he must feel fighting for the rights of the animals he loves so much. I'm sure it goes against his natural instinct but he thinks it could be a better way of getting them the protection they need.
I guess at this stage, animals are lucky to have what little land they have left, if hunting needs to fall under the umbrella of wildlife protection, so be it. But that attitude will have to change at some point, the sense of entitlement and destruction of natural resources will have to stop, all species will gain REAL protection once that happens.

For a long time, we humans have deemed ourselves superior to every other existent life form. This thread was made to find the reason or reasons why humans think this, as well as other behaviors deemed special to modern humans.

Agreed. It is better to just let natural selection take its place instead of "helping" the animals by repairing their injuries or killing them. 

In our past (at least in the societies/tribes respectful of nature), whenever a human would cross paths with a injured/nearly-dead animal, the human would pay his respects and leave the animal to its future fate.

Now it seems like we want to actively "help" animals heal whenever we cross paths with one, even though it harms the injured animal's risks of foraging/hunting/grazing in the future (and possibly harms natural selection if the most fittest specimens find it near-impossible to hunt a single prey.) 

We, as humans, do not understand the impact that our actions display upon animals and nature in general. Conservation groups' efforts are only about preventing others from poaching and "helping" the animals. In other words, they would rather employ more forest guards and rangers (i.e. more control of natural landscapes/parks), than to leave the place alone.

The short and most beneficial answer to conservation?

To completely leave the natural landscapes alone.

------------------------------------------------------------

Another question would be: then won't that increase the frequency of poachers/hunters in the area? That would be the hardest question to answer.

A lot of society's various "illegal profits" are geared towards the absorption and consumption of rich animal materials such as ivory, fur skins, and various bones. Most of the meat is simply thrown away because, as Peter mentioned earlier on an AvA forum, we already have a surplus of meat; why produce any more?

We (and most societies) do not use all of the animal as Native Americans and some African/Pacific natives do.

To the question in hand, the best way to reduce poaching/hunting is to either:

-Gauge profits so that rare animal materials don't earn income or profit in any way. (which will prevent the poachers/hunters from getting incentives for trying to sell that rhino horn or lion tooth.)

-Totally eliminate the monetary system and corruption of society. (Best solution to most world problems in general, including this.)

These ideas would best solve a huge reduction in poaching/hunting, in my opinion.

Today, I saw some very unusual photograph from fb. A bond between Leopard and Domestic cow from India (Narasipuram, coimbatore ). This is an unusual sighting. We have seen some rare images where predators from different species share food and live with each other (for short time) . But it is very rare to see love bond between a prey and predators.
You can share such moments in this thread.







Image owned by Manoj Thaker

Most of you may have seen the great work @tigerluver is doing, estimating male tiger size based off females so I figured that I'd move all of them here and continue the discussion.

So far




Tigerluver writes "A while ago, I took the length of the two from the picture and estimated that Amur male by isometry. From the photo, he is 1.17x longer, which equates to 1.6x in weight. Taking the 115 kg average for Amur female in STP, the estimate would be 185 kg for that male. "

"the Amur in that photo has chest diameter 1.23x the female, translating to 1.86x the mass and 214 kg with the 115 kg number for the female. Averaging length and chest diameter gives 200 kg for the male, which I guess would be a large Amur male based on what we have now. "



2 year old Pandit and mother, Sharmili.

Tigerluver "Lengthwise, he's 1.18x length without correcting for perspective and angle. Maybe 1.13 would be a corrected value.

In terms of chest diameter, the son 1.20x his mother's size with correction. Perhaps 1.15x can be the number to put here to deal with perspective.

Same methods as above result in a length estimate of 188 kg, chest estimate of 198 kg, averaging 193 kg. "




A very young saturn with his female from Tadoba

Tigerluver "I split the image and straightened the tigers.

He's 1.12x her length and 1.20x her chest diameter. 


Length based estimate (if female is 130 kg) is 183 kg and chest diameter estimate (again assuming the female is 130 kg) is 225 kg, averaging 204 kg. "



The Duisburg Zoo male Amur tiger

Tigerluver "I measured the female to be around 160 cm, which seems like a ~115 kg female basing off the slightly shorter female Jasmin and the STP tigresses. So the male is 1.31x the female's length and 1.32x the female's chest girth from examining the photo.

If I were to estimate the Duisburg male based on this female, we get:

Length based: 1.31^3 * 115 kg = 260 kg
Chest diameter based: 1.32^3 * 115 kg = 265 kg
 
Now with his body length I can apply some estimates from data of other male tigers.

Based on the STP males, isometrically scaling his 210 cm frame based on the average of 7 males of the study (avg. body length = 196 cm, avg. mass = 182 kg), he would weigh 224 kg. An issue with using the STP males is that the wild Amur seems have lost a lot of the robusticity found in captive Amurs and the rest of the tiger subspecies. In other words, STP males are very lanky compared to their captive Amur cousins, and the Duisburg male would likely be more like other captives Amurs rather than the wild STP males. The Duisburg male is also taller proportionately than the STP males.

To account for height in the equation, I used the following data. 6 STP males averaged 94 cm at the shoulder and weighed 184 kg. Isometrically estimating Mr. Duisburg from these numbers and his 110 cm height results in a mass of 295 kg. This somewhat accounts for the underestimation by the body length estimate. Combining both body length and height estimates gives a mass of 260 kg. Coincidentally on par with the estimate based on the female by his side. 

Based on some captive Amurs, the mass values are bit higher. Looking off the table @GuateGojira provided in the Amur tiger thread and the three males of Christiansen, I came up with a average body length and weight for captive Amurs where were as follows:

n = 6
Body length = 195 cm
Mass = 223 kg


Isometrically scaling the Duisburg male from these figures results in a mass of about 280 kg.

Had he had Bengal tiger proportions, he would likely be heavier and significantly so at 280-320 kg. Comparing him to Sauraha for example, shows a body length with the potential to harbor a 320 kg cat. The problems I see with using Bengal tigers for comparisons is that the Duisburg male for one, does not seem as bulky as Bengal tigers and the fact that he still is an Amur in the end, and would likely keep to their somewhat leaner built. 

I have to revisit the photos, however. In the latter two photos the Duisburg males look bulkier than the first photo. Measuring the chest diameter/body length ratio, he is at least 5% less bulky in the photo with the female than in the photos he was alone. Bulking him up in the photo analysis and comparing him with the female gives a chest diameter mass of 306 kg. Averaging this value with his presumably constant body length then gives an average mass of 283 kg.

All in all, isometry based on Amurs gave me a mass range of 260-280 kg for the the Duisburg male.

(I tried a new method of creating clear subtopics without needing subheading by bolding the first few words of the new subtopic. I hope it made the read easier.) "



T25 with female T19, said to be larger than her sister, T18 (weighed 170kg)

Tigerluver "First what is on the plain of the image (no adjustments). T25 is 1.085x longer and 1.093x larger in chest diameter.

In terms of correction, T25 has his head more tucked in, so from the plain of the image one could say he is 1.09x longer.

Now in terms of perspective, T25 is further back than T17. I think compensating by increasing the length difference to 1.11x and girth difference to 1.113x would be okay, maybe a bit too conservative but we'll stick with this for the first set of calculations.

So to estimate mass:
Length based mass = 1.11^3 * 170 kg = 233 kg
Chest based mass = 1.113^3 * 170 kg = 234 kg
Both values are functionally the same.

Now a caveat is that if you look at how much difference being even a meter behind another object will shrink the object further back, the aforementioned compensation is likely too little. Maybe compensating both difference ratios to 1.13x-1.15x would be more accurate, which is a mass of 245-260 kg, similar to T24. "



Kingfisher and Umarjhola Female from Kahna

tigerluver "Top photo:
Without correcting anything for perspective:
The male is 1.08x the length of the female but the male is at a shortening angle.
His chest diameter is 1.41x that of the female's, however.

Bottom photo:
Male's length in this one is 1.40x the female's, but the female is at a shortening angle.
Male's chest girth is 1.37x that of the female's.

Not exactly sure how much to compensate for the male being closer in the photo. Perhaps the male is 1.10x the female's length (average the two photos and deduct for his positioning) and the his girth is 1.25x the female's with the same compensations. 

So say the female is 130 kg, isometry results in:
Length based: 1.10^3 * 130 kg = 173 kg
Chest diameter: 1.25^3 * 130 kg = 254 kg
Avg. = 214 kg

If I compensated the male too much, we could say 1.15x length (198 kg) and 1.3x girth (286 kg) at best, which using the above method would come to 242 kg. I'd put this number as the high end and would prefer the more conservative numbers above. All in all, the male is stockier than the female but not much longer. "





This is what we have so far, I'll continue to post what I can find and hopefully we can use this technique more often.
My other thought would be if there is any correlation for limb girth or shoulder height to body weight.

Once again, GREAT WORK @tigerluver

Recently I've been seeing quite alot of human bashing mostly relating to our treatement of other lifeforms on this planet, but to what extent should humans take the blame? We are blamed for our takeover of land, once ruled by nature, but it's human nature to reproduce and spread across the globe. Does this force us to reprogramme ourselves as human beings? Of course there is a limit but then there comes the question, to what extent can you blame humans for doing what's natural to us? People always want more. Our development can only go forward, maybe not morally, but by any means neccesary to further our position on this planet. That's humanity. It may be a cynical view but it is one of I believe complete truth. Yes these problems all stem from us, but this cucoon that some people have of a perfect world of nature engulfing the land seems to be a false hope taken too far by marketing. There is no way that humans are not to blame for the hardship other organisms face, but how much. We are far from perfect and even the most compassionate people who always look out for another person or lifeforms on this planet, has that voice in the back of their head wanting more, which is not easy to fight...

So my question is, to what extent should the human race be blamed for the hardships other lifeforms face on this planet?

https://www.sciencedaily.com/releases/20...m=facebook 
 
Date:
May 11, 2016
University of Pennsylvania
A doctoral student at the University of Pennsylvania has identified a new species of fossil dog. The specimen, found in Maryland, would have roamed the coast of eastern North America approximately 12 million years ago, at a time when massive sharks like megalodon swam in the oceans.