Jul 18, 2016 11:23 PM
Why You Should Believe in the Digital Afterlife
http://www.theatlantic.com/science/archi...ke/491105/
EXCERPT: [...] But can the technology be scaled up to preserve someone’s consciousness on a computer? The human brain has about a hundred billion neurons. The connectional complexity is staggering. By some estimates, the human brain compares to the entire content of the internet. It’s only a matter of time, however, and not very much at that, before computer scientists can simulate a hundred billion neurons. [...]
No existing scanner can measure the pattern of connectivity among your neurons, or connectome, as it’s called. MRI machines scan at about a millimeter resolution, whereas synapses are only a few microns across. We could kill you and cut up your brain into microscopically thin sections. Then we could try to trace the spaghetti tangle of dendrites, axons, and their synapses. But even that less-than-enticing technology is not yet scalable. Scientists like Sebastian Seung have plotted the connectome in a small piece of a mouse brain, but we are decades away, at least, from technology that could capture the connectome of the human brain.
Assuming we are one day able to scan your brain and extract your complete connectome, we’ll hit the next hurdle. In an artificial neural network, all the neurons are identical. They vary only in the strength of their synaptic interconnections. That regularity is a convenient engineering approach to building a machine. In the real brain, however, every neuron is different. To give a simple example, some neurons have thick, insulated cables that send information at a fast rate. You find these neurons in parts of the brain where timing is critical. Other neurons sprout thinner cables and transmit signals at a slower rate. Some neurons don’t even fire off signals—they work by a subtler, sub-threshold change in electrical activity. All of these neurons have different temporal dynamics.
The brain also uses hundreds of different kinds of synapses. [...] Although Cajal didn’t realize it, some neurons actually do connect directly, membrane to membrane, without a synaptic space between. These connections, called gap junctions, work more quickly than the regular kind and seem to be important in synchronizing the activity across many neurons.
Other neurons act like a gland. Instead of sending a precise signal to specific target neurons, they release a chemical soup that spreads and affects a larger area of the brain over a longer time. I could go on with the biological complexity. These are just a few examples.
A student of artificial intelligence might argue that these complexities don’t matter. You can build an intelligent machine with simpler, more standard elements, ignoring the riot of biological complexity. And that is probably true. But there is a difference between building artificial intelligence and recreating a specific person’s mind. If you want a copy of your brain, you will need to copy its quirks and complexities, which define the specific way you think. [...] you would need a scanning device that can capture what kind of neuron, what kind of synapse, how large or active of a synapse, what kind of neurotransmitter, how rapidly the neurotransmitter is being synthesized and how rapidly it can be reabsorbed. Is that impossible? No. But it starts to sound like the tech is centuries in the future rather than just around the corner. Even if we get there quicker, there is still another hurdle. [...] And yet I remain optimistic....
Real reason turtles have shells
https://www.sciencedaily.com/releases/20...171312.htm
RELEASE: It is common knowledge that the modern turtle shell is largely used for protection. No other living vertebrate has so drastically altered its body to form such an impenetrable protective structure as the turtle. However, a new study by an international group of paleontologists suggests that the broad ribbed proto shell on the earliest partially shelled fossil turtles was initially an adaptation, for burrowing underground, not for protection. Paleontologist Tyler Lyson from the Denver Museum of Nature & Science is among the scientists that helped make this discovery.
"Why the turtle shell evolved is a very Dr. Seuss-like question and the answer seems pretty obvious -- it was for protection," said Dr. Lyson, lead author of Fossorial Origin of the Turtle Shell, which was released today by Current Biology. But just like the bird feather did not initially evolve for flight, the earliest beginnings of the turtle shell was not for protection but rather for digging underground to escape the harsh South African environment where these early proto turtles lived."
The early evolution of the turtle shell had long puzzled scientists. "We knew from both the fossil record and observing how the turtle shell develops in modern turtles that one of the first major changes toward a shell was the broadening of the ribs," said Dr. Lyson. While distinctly broadened ribs may not seem like a significant modification, it has a serious impact on both breathing and speed in quadrupedal animals. Ribs are used to support the body during locomotion and play a crucial role in ventilating the lungs. Distinctly broadened ribs stiffen the torso, which shortens an animals stride length and slows it down, interfering with breathing.
"The integral role of ribs in both locomotion and breathing is likely why we don't see much variation in the shape of ribs," said Dr. Lyson. "Ribs are generally pretty boring bones. The ribs of whales, snakes, dinosaurs, humans, and pretty much all other animals look the same. Turtles are the one exception, where they are highly modified to form the majority of the shell."
A big breakthrough came with the discovery of several specimens of the oldest (260- million-year-old) partially shelled proto turtle, Eunotosaurus africanus, from the Karoo Basin of South Africa. Several of these specimens were discovered by two of the study's coauthors, Drs. Roger Smith and Bruce Rubidge from the University of Witwatersrand in Johannesburg. But the most important specimen was found by a then 8-year-old South African boy on his father's farm in the Western Cape of South Africa. This specimen, which is about 15 cm long, comprises a well preserved skeleton together with the fully articulated hands and feet.
"I want to thank Kobus Snyman and shake his hand because without Kobus both finding the specimen and taking it to his local museum, the Fransie Pienaar Museum in Prince Albert, this study would not have been possible," said Dr. Lyson.
http://www.theatlantic.com/science/archi...ke/491105/
EXCERPT: [...] But can the technology be scaled up to preserve someone’s consciousness on a computer? The human brain has about a hundred billion neurons. The connectional complexity is staggering. By some estimates, the human brain compares to the entire content of the internet. It’s only a matter of time, however, and not very much at that, before computer scientists can simulate a hundred billion neurons. [...]
No existing scanner can measure the pattern of connectivity among your neurons, or connectome, as it’s called. MRI machines scan at about a millimeter resolution, whereas synapses are only a few microns across. We could kill you and cut up your brain into microscopically thin sections. Then we could try to trace the spaghetti tangle of dendrites, axons, and their synapses. But even that less-than-enticing technology is not yet scalable. Scientists like Sebastian Seung have plotted the connectome in a small piece of a mouse brain, but we are decades away, at least, from technology that could capture the connectome of the human brain.
Assuming we are one day able to scan your brain and extract your complete connectome, we’ll hit the next hurdle. In an artificial neural network, all the neurons are identical. They vary only in the strength of their synaptic interconnections. That regularity is a convenient engineering approach to building a machine. In the real brain, however, every neuron is different. To give a simple example, some neurons have thick, insulated cables that send information at a fast rate. You find these neurons in parts of the brain where timing is critical. Other neurons sprout thinner cables and transmit signals at a slower rate. Some neurons don’t even fire off signals—they work by a subtler, sub-threshold change in electrical activity. All of these neurons have different temporal dynamics.
The brain also uses hundreds of different kinds of synapses. [...] Although Cajal didn’t realize it, some neurons actually do connect directly, membrane to membrane, without a synaptic space between. These connections, called gap junctions, work more quickly than the regular kind and seem to be important in synchronizing the activity across many neurons.
Other neurons act like a gland. Instead of sending a precise signal to specific target neurons, they release a chemical soup that spreads and affects a larger area of the brain over a longer time. I could go on with the biological complexity. These are just a few examples.
A student of artificial intelligence might argue that these complexities don’t matter. You can build an intelligent machine with simpler, more standard elements, ignoring the riot of biological complexity. And that is probably true. But there is a difference between building artificial intelligence and recreating a specific person’s mind. If you want a copy of your brain, you will need to copy its quirks and complexities, which define the specific way you think. [...] you would need a scanning device that can capture what kind of neuron, what kind of synapse, how large or active of a synapse, what kind of neurotransmitter, how rapidly the neurotransmitter is being synthesized and how rapidly it can be reabsorbed. Is that impossible? No. But it starts to sound like the tech is centuries in the future rather than just around the corner. Even if we get there quicker, there is still another hurdle. [...] And yet I remain optimistic....
Real reason turtles have shells
https://www.sciencedaily.com/releases/20...171312.htm
RELEASE: It is common knowledge that the modern turtle shell is largely used for protection. No other living vertebrate has so drastically altered its body to form such an impenetrable protective structure as the turtle. However, a new study by an international group of paleontologists suggests that the broad ribbed proto shell on the earliest partially shelled fossil turtles was initially an adaptation, for burrowing underground, not for protection. Paleontologist Tyler Lyson from the Denver Museum of Nature & Science is among the scientists that helped make this discovery.
"Why the turtle shell evolved is a very Dr. Seuss-like question and the answer seems pretty obvious -- it was for protection," said Dr. Lyson, lead author of Fossorial Origin of the Turtle Shell, which was released today by Current Biology. But just like the bird feather did not initially evolve for flight, the earliest beginnings of the turtle shell was not for protection but rather for digging underground to escape the harsh South African environment where these early proto turtles lived."
The early evolution of the turtle shell had long puzzled scientists. "We knew from both the fossil record and observing how the turtle shell develops in modern turtles that one of the first major changes toward a shell was the broadening of the ribs," said Dr. Lyson. While distinctly broadened ribs may not seem like a significant modification, it has a serious impact on both breathing and speed in quadrupedal animals. Ribs are used to support the body during locomotion and play a crucial role in ventilating the lungs. Distinctly broadened ribs stiffen the torso, which shortens an animals stride length and slows it down, interfering with breathing.
"The integral role of ribs in both locomotion and breathing is likely why we don't see much variation in the shape of ribs," said Dr. Lyson. "Ribs are generally pretty boring bones. The ribs of whales, snakes, dinosaurs, humans, and pretty much all other animals look the same. Turtles are the one exception, where they are highly modified to form the majority of the shell."
A big breakthrough came with the discovery of several specimens of the oldest (260- million-year-old) partially shelled proto turtle, Eunotosaurus africanus, from the Karoo Basin of South Africa. Several of these specimens were discovered by two of the study's coauthors, Drs. Roger Smith and Bruce Rubidge from the University of Witwatersrand in Johannesburg. But the most important specimen was found by a then 8-year-old South African boy on his father's farm in the Western Cape of South Africa. This specimen, which is about 15 cm long, comprises a well preserved skeleton together with the fully articulated hands and feet.
"I want to thank Kobus Snyman and shake his hand because without Kobus both finding the specimen and taking it to his local museum, the Fransie Pienaar Museum in Prince Albert, this study would not have been possible," said Dr. Lyson.
