Sunday, September 11, 2005

Titan moon occupies 'sweet spot', etc

Here are science news items with my comments in square brackets:

Titan moon occupies 'sweet spot', BBC, Paul Rincon, 9 September 2005. ... Earth and Saturn's moon Titan show striking similarities because both occupy "sweet spots" in our Solar System, researchers have said. Many processes that occur on Earth also take place on this moon, say scientists participating in the US-European Cassini-Huygens mission. Wind, rain and volcanism and tectonic activity all seem to play a role in shaping Titan's surface. One scientist even sees a way that life could survive on the freezing world. "Titan is perhaps the most Earth-like place in the Solar System other than Earth, in terms of the balance of processes," says Jonathan Lunine ... [As the article says, "on the surface of Titan ... temperatures are about -178C (-289F)", "the chemistry that drives ... processes is radically different between the two worlds," and Titan has a diameter of only 5150 km (compared to Earth's 12,756 km), so astrobiologists like Lunine have a very flexible definition of "Earth-like"! When assessing the claims of astrobiologists, it is worth remembering origin of life specialist Jeffrey L. Bada's observation of astrobiology: "one of the field's attractions was money--and lots of it":

"Today, it seems nearly everyone is an astrobiologist. A decade ago, I knew essentially none. Why this sudden obsession with a field that encompasses so many diverse areas in both the physical and life sciences? So far, life has not been found to exist away from Earth, although the surge in interest in astrobiology suggests there is intense optimism within at least parts of the science community that this singularity will change in the future. But scientific curiosity alone likely cannot explain the explosive growth of astrobiology. After reading The Living Universe: NASA and the Development of Astrobiology, I came to the conclusion that one of the field's attractions was money--and lots of it." (Bada J.L., "A Field with a Life of Its Own." Review of "The Living Universe: NASA and the Development of Astrobiology," by Steven J. Dick and James E. Strick, Rutgers University Press: Piscataway NJ, 2004. Science, Vol. 307, 7 January 2005, p.46)

But at least the article makes the point that when considering "a balance between size, or mass, and distance from the Sun" of the "three planets in the inner Solar System: Venus, Earth and Mars. ...Venus is about the same size as Earth. But it is so close to the Sun that any water it had must have boiled off. As such, there is no hydrological cycle and no tectonic activity ... Mars is distant enough from the Sun to retain water. But its small size caused it to cool quickly, turning water to ice and ending large-scale geological activity. Earth occupies an intermediate position - the "sweet spot". I have added that part of the article to my "Problems of Evolution" book outline, PE 6.4.1 "Earth's fitness for life ... Circumstellar Habitable Zone."]

Study: Bumblebees Advanced Learners, Discovery News, Larry O'Hanlon, Sept. 8, 2005 - Bumblebees are a brainy bunch, according to new study showing that the insects watch other bumblebees to learn what flowers to dine on. The ability to learn simply by watching is usually accorded to only certain birds, marine mammals and primates. This new work shows that the old saying "monkey see, monkey do" applies even to some insects. "Bees can learn things on their own or learn from others," said bumblebee researcher Bradley Worden of the University of Arizona. Worden is a co-author of a paper on the matter in an upcoming issue of Biology Letters of the Royal Society ...." The work on bumblebees by Worden is just another nail in the coffin of the idea that there is a fundamental difference in mental abilities between vertebrates and invertebrates, said [Lars] Chittka. "The idea that insects are simple reflex machines, because of their short life span and miniature brains, has to be abandoned."... [See also Livescience. Evolutionists oftrn claim there is no distinction in kind (just degree) between humans and animals, e.g. this claim of Gould's and Berlinski's reply:

"Among other things, medieval thinkers believed that human beings were unique in ways that were absolute and inviolable. This doctrine many modern biologists have emphatically rejected. `The western world,' Stephen Jay Gould remarks, `has yet to make its peace with Darwin.' The great impediment to this reconciliation, he goes on to add ...
`lies in our willingness to accept continuity with ourselves and nature, our ardent search for a criterion to assert our own uniqueness. Chimps and gorillas have long been the battleground of our search of uniqueness, for if we could establish an unambiguous distinction - of kind, rather than degree between ourselves and our closest relatives, we might gain the justification long sought for our cosmic arrogance. Educated people now accept the evolutionary continuity between human and apes. But we are so tied to our philosophical and religious heritage that we still seek a criterion for a strict division between our abilities and those of a chimpanzee.' [Gould S.J., "A Matter of Degree," in "Ever Since Darwin: Reflections in Natural History," [1978], Penguin: London, 1991, reprint, pp.50-51]
Now I quote all this not merely because Gould holds a chair at Harvard and I do not; although this made the target all therefore tempting, but because Gould represents a charming intelligence corrupted by a shallow system of belief. No distinction in kind rather than degree between ourselves and the chimps? No distinction? Seriously, folks? Here is a simple operational test: The chimpanzees invariably are the ones behind the bars of their cages. There they sit, solemnly munching bananas, searching for lice, aimlessly loping around, baring their gums, waiting for the experiments to begin. No distinction? Chimpanzees cannot read or write; they do not paint, or compose music, or do mathematics; they form no real communities, only loose-knit wandering tribes; they do not dine and cannot cook; there is no record anywhere of their achievements; beyond the superficial, they show little curiosity; they are born, they live, they suffer and they die. No distinction? ... there is not a trace in the animal world of virtually any of the powerful and poorly understood powers and properties of the human mind; in all of history no animal has stood staring at the night sky in baffled and respectful amazement. ... One may insist, of course, that all this represents difference merely of degree. Very well. Only a difference of degree separates man from the Canadian Goose Individuals of both species are capable of entering the air unaided and landing some distance from where they started." (Berlinski D., "Good as Gould," in "Black Mischief: Language, Life, Logic, Luck," Harcourt Brace Jovanovich: Boston MA, Second Edition, 1988, pp.293-295. Emphasis original)

even down to claiming (as here) that "there is [no] ... fundamental difference in mental abilities between vertebrates [e.g. humans] and invertebrates [e.g. insects]"! But according to my animal behaviour textbook (Alcock J., "Animal Behavior: An Evolutionary Approach," Sinauer Associates: Sunderland MA, Fifth edition, 1993, pp.25ff), the original distinction between "instincts" being innate and "learning" being acquired from experience, has broken down, since some instincts can be modified by experience. So the fact that a bumblebee can learn an essential behaviour from other bumblebees, does not seem to me to be necessarily learning in the same sense that a higher animal like a dog can learn non-essential tricks or a human can learn table manners. It could still be an innate instinct programmed to copy other bumblebees in that behaviour. What would need to be shown is that a bumblebee can learn non-essential varied behaviours from another bumblebee (or rather a realistic imitation since a bumblebee that could do non-essential behaviours would have already learned them), like a dog can learn tricks.]

Water crisis looms as Himalayan glaciers melt, CNN, September 9, 2005. NEW DELHI, India (Reuters) -- Imagine a world without drinking water. It's a scary thought, but scientists say the 40 percent of humanity living in South Asia and China could well be living with little drinking water within 50 years as global warming melts Himalayan glaciers, the region's main water source. The glaciers supply 303.6 million cubic feet every year to Asian rivers, including the Yangtze and Yellow rivers in China, the Ganga in India, the Indus in Pakistan, the Brahmaputra in Bangladesh and Burma's Irrawaddy. But as global warming increases, the glaciers have been rapidly retreating, with average temperatures in the Himalayas up 1 degree Celsius since the 1970s. A World Wide Fund report published in March said a quarter of the world's glaciers could disappear by 2050 and half by 2100. "If the current scenario continues, there will be very little water left in the Ganga and its tributaries," Prakash Rao, climate change and energy program coordinator with the fund in India [said] ... [The report said: "The rapid melting of Himalayan glaciers will first increase the volume of water in rivers, causing widespread flooding," said Jennifer Morgan, director of the WWF's global climate change program. "But in a few decades this situation will change and the water level in rivers will decline, meaning massive economic and environmental problems for people in western China, Nepal and northern India." The report included: "Himalayan glaciers feed into seven of Asia's greatest waterways - the Ganges, Indus, Brahmaputra, Salween, Mekong, Yangtze and Yellow rivers - ensuring a year-round water supply to hundreds of millions of people. ... the WWF stressed the need to recognise climate change as an issue that seriously threatens security and development. ... the world faces an economic and development catastrophe if the rate of global warming isn't reduced," ... "truly dangerous" levels of climate change could be reached in just over 20 years. ...As glacier water-flows dwindle, the energy potential of hydroelectric power will decrease, causing problems for industry. Agriculture will also suffer, as reduced irrigation means lower crop yields." This is more evidence that we are entering the Great Tribulation (Mat. 24:21 (KJV) "For then shall be great tribulation [Gk. megale thlipsis, "great pressure"], such as was not since the beginning of the world to this time, no, nor ever shall be" (cf. Mk 13:19 & Lk 21:23; Rev 7:14 KJV)], in the midst of which Jesus will return (Mat 24:22,29-30; Mk 13:20,26; Lk 21:25-27) (see tagline quote)]

Stephen E. Jones, BSc (Biol).
"Problems of Evolution"


"[MATTHEW 24:]21,22 ... `for then there shall be great tribulation, such as there has never been since the beginning of the world until now, and as there shall never be again. And if those days were not cut short no one would be saved. But for the sake of the elect those days shall be cut short.'... Jesus is here speaking about a tribulation that will characterize `those days,' a tribulation such as has never been and never again shall be, a very brief period of dire distress that shall occur immediately before his return (see verses 29-31). It is the period mentioned also in Rev. 11:7-9; 20:3b, 7-9a. For the sake of God's chosen ones-see ... on Eph. 1:4-in order that not all might have to die a violent death, the days of this final tribulation shall be cut short. Herein, too, the love of God is made manifest. It should hardly be necessary to add that justice is not done to the concept of this tribulation, which immediately precedes `the end' of the world's history and which surpasses any other distress in its intensity, if it is referred solely to the sorrows experienced during the fall of Jerusalem." (Hendriksen W., "The Gospel of Matthew: New Testament Commentary," [1973], The Banner of Truth Trust, 1982, reprint, pp.859-860. Emphasis original)

4 comments:

John Umana said...

THE FUNDAMENTAL QUESTIONS OF ASTROBIOLOGY
by John Umana http://johnumana4.blogspot.com/

I thought I'd share my current thinking on the deep questions of astrobiology and the emergence of life:

(1) There is no other life in this sun system. Mars contains no life and never did, notwithstanding that 70% of scientists polled believe that there is or was life on Mars at one time. This conventional wisdom is mistaken. Saturn's moon Titan contains no life and never did. No other planet or object, no comet, no asteroid in this sun system contains any form of life. Europa does not contain liquid seas under the ice. When NASA gets there after 2010 or so, we’ll see that there are no fishes swimming around. Only Earth in this sun system contains seas of liquid water at this time, though Mars once did have shallow seas as the rovers Spirit and Opportunity and the orbiters have found. Where did/does the water come from on Earth and (billions of years ago) on Mars? Volcanoes produce large amounts of water steam, and they are largely responsible for Earth's oceans. Other released gases from volcanoes included carbon dioxide (CO2), sulfur dioxide (SO2), hydrochloric acid (HCl), hydrogen fluoride (HF), hydrogen sulfide (H2S), carbon monoxide (CO), molecular hydrogen gas (H2), NH3, methane (CH4), silicon tetrafluoride (SiF4), and minor amounts of nitrogen (N2) and argon (Ar). But no oxygen. … And no life. Plenty of hydrogen, however, is a great start. The name is derived from the Greek ‘hydro genes,’ meaning water forming. Though most of our water came from volcanoes, carbonaceous chondrites, among the most primitive objects in our sun system, contain water locked up in phyllosilicate minerals with the water content making up about 10% by weight of the meteorites. Comets and meteorites also gave us some water.

(2) In my respectful opinion, the Universe including our galaxy is teeming with life. All life throughout the vast cosmos is nucleotide, DNA-based. (OK, you're right, I don't have the proof today but hoping that mankind will come up with the proof during this new millenium.)

(3) In my respectful opinion, the Universe including our galaxy is teeming with intelligent life. (The reason SETI is not picking them up is they are unlikely to be communicating by radio or any type of electromagnetic communication -- far too slow for the distances involved.)

(4) Extraterrestrial astronauts did not “seed” mankind or life on Earth. The theory of panspermia is way off the mark. No need to keep worrying about whether comets could have carried spores of life here; that's not what happened and the distances are too vast for a living spore to hitch a ride on a comet in any event. There is no life beyond Earth for a long, long ways.

(5) Darwin's/Wallace's theory of the evolutionary theory of common ancestry is proved conclusively by the convergence of the entire scientific and fossil record, including paleontology, molecular biology, genetics, mitochondrial DNA, Y-chromosome DNA, comparative anatomy and physiology, biogeography, geology and archaeology. I do not believe there was a single common ancestor RNA strand, rather; there was differentiation right from the first period of emergence into what would become the plant and animal kingdoms. No common ancestor with life on other habitable worlds. Life emerged separately and independently on Earth.

(6) The Darwinian theory of "natural selection" as the mechanism for origin of the species is unsubstantiated, overly simplistic, and runs contrary to what is observed in modern microbiology. It is bad science as theory of emergence or origin of species, though natural selection is a true force of nature and accounts for such phenomena as pesticide resistance of insects (e.g., the mosquitos that survive an application of a given pesticide eventually develop an immunity to it over time) or the resistance of bacteria to antibiotics. Natural selection (NS) is not the causative mechanism for the evolution of a single species on Earth or anywhere else. The neo-Darwinists are way, way off the mark as to the specific mechanism of evolution as microbiology is beginning to demonstrate. NS was an interesting guess back in the 1800’s. Less interesting today with microbiology. Whatever the right answer is as to emergence and origin of species, it isn't NS.

(7) Life emerged on Earth independently of other habitable worlds -- just shy of 4.0 billion years ago at the tail end of the Heavy Bombardment.

(8) Where/how first life emerged on Earth? Just shy of 4 billion years ago. Pick an area where the critical amino acids are found. Prep needed. Areas under the shallow seas at that time and sheltered puddles where seas met rocky shore, protected from UV rays. Black smokers come much later; emergence of life there was much more difficult. Sheltered areas protected from lethal and destabilizing UV rays including areas under the seas. Still massive comet strikes nearly every day or few days, equivalent to thermonuclear blasts, sending massive seismic shock waves throughout mantle and core. Temperature out a balmy 200-300 degrees; more inhospitable as approach areas adjacent to live volcanos. Pre-biotic Earth temperature range roughly -288 F to +260 F. At night, temperatures dropped sharply as on the moon without protective atmosphere. No free oxygen to speak of on Earth. No ozone screen 10-15 miles up in atmosphere to protect emergence of first life from lethal UV. Earth highly radioactive as remnant of solar nebula, creating enormous challenge to emergence of first RNA strand; no membrane at first; highly unstable molecule. Thin atmosphere of H2O, CO2, SO2, N2. Stark sunlight. Pristine earth. No blue sky. Whispy clouds occasionally high up. More like sunlight falling across face of moon or Mars (but no pink sky like Mars). Because of gamma radiation, UV and wild temperature swings, only rapidly reproducing self-replicating strands possible, containing backup DNA files for self-repair when damaged by radiation or UV -- until Earth cools off radioactively within the next few billion years (as of 4 bya). That's the reason why there was no evolution beyond single cells until 583 million years ago or so with emergence of Ediacara biota and some 40 million years later with the Cambrian explosion of life. [John Umana All rights reserved.]

Have a good day!

Stephen E. Jones said...

John

>THE FUNDAMENTAL QUESTIONS OF ASTROBIOLOGY
by John Umana http://johnumana4.blogspot.com/
>
>I thought I'd share my current thinking on the deep questions of astrobiology and the emergence of life:

Thanks for your comments on "astrobiology", formerly called "exobiology", the "science of extraterrestrial life", which Simpson noted *40+ years ago* (and is still the case today) is a "`science' [that] has yet to demonstrate that its subject matter exists":

"There is even increasing recognition of a new science of extraterrestrial life, sometimes called exobiology-a curious development in view of the fact that this `science' has yet to demonstrate that its subject matter exists!" (Simpson G.G., "The Nonprevalence of Humanoids," in "This View of Life," 1964, pp.253-254)

>(1) There is no other life in this sun system. Mars contains no life and never did ...

I don't rule out that there may have been (and may still be) life on Mars, but if there was/is, I predict it will have come from Earth or vice-versa. IOW, life only even began *once*, not only in the Solar System, not only in our galaxy, but in the entire *Universe*.

>(2) In my respectful opinion, the Universe including our galaxy is teeming with life. ...

My opinion is that the only life in the entire *Universe* is on Earth (or possibly was, or still is, on Mars). That is life began (i.e. was created) *once* in the entire Universe, either on Earth, or on Mars and was then transported to Earth via asteroid impact ejecta.

>(3) In my respectful opinion, the Universe including our galaxy is teeming with intelligent life. ...

In mine its not. See above.

>(4) Extraterrestrial astronauts did not “seed” mankind or life on Earth. ...

Agreed. In my view there never were any "Extraterrestrial astronauts".

>(5) Darwin's/Wallace's theory of the evolutionary theory of common ancestry ...

There is *no* Darwin's/Wallace ... theory of common ancestry." A scientific theory is named after its first proposer. And Darwin, in the third edition (1861) of his Origin of Species, belatedly acknowledged that Lamarck ~50 years before him, proposed the first scientific theory of common ancestry, "that all species, including man, are descended from other species":

"Lamarck was the first man whose conclusions on the subject excited much attention. This justly celebrated naturalist first published his views in 1801; he much enlarged them in 1809 in his Philosophie Zoologique, and subsequently, in 1815, in the Introduction to his Hist. Nat. des Animaux sans Vertebres. In these works he upholds the doctrine that all species, including man, are descended from other species." (Darwin C.R., "The Origin of Species by Means of Natural Selection," [1872], 6th Edition, J.M. Dent & Sons: London, 1928, reprint, pp.7-8)

While Darwin added other evidence in support of Lamarck's theory of common ancestry, it does not cease to be Lamarck's theory, anymore than Einstein's theory of Relativity ceases to be his because later scientists have provided further evidence in support of it.

>(6) The Darwinian theory of "natural selection" as the mechanism for origin of the species is unsubstantiated, overly simplistic, and runs contrary to what is observed in modern microbiology. …

My position is that "The Darwinian theory of" the "natural selection" of random micromutations (NSRM) is not *the* "mechanism for origin of the species" but it might well be "the mechanism for [the] origin of" *some* "species". Although there is little (if any) evidence of that.

>(7) Life emerged on Earth independently of other habitable worlds -- just shy of 4.0 billion years ago at the tail end of the Heavy Bombardment (LHB).

The Late Heavy Bombardment was between 4.0-3.8 bya [http://tinyurl.com/qd9lr; http://tinyurl.com/faa9k], and its giant impacts would have repeatedly melted the crust and boiled the ocean, sterilizing it of life. Although there may have been quiet intervals where the Earth cooled down [http://tinyurl.com/zh2o3]

The earliest evidence of life on Earth is carbon 13 isotopes dated at ~3.85 bya [http://tinyurl.com/eu6om]. But this too is disputed [http://tinyurl.com/osu68]. The earliest undisputed actual fossils (cyanobacteria) are 3.5 bya [http://tinyurl.com/kjffr].

If life did begin ~3.85 bya, then either the LHB ended before then, or it was not as severe, or life began (or was later sheltered) somewhere on Earth (e.g. deep underground) where crustal melting and ocean boiling from giant impacts did not occur.

(8) Where/how first life emerged on Earth? Just shy of 4 billion years ago. Pick an area where the critical amino acids are found. Prep needed. Areas under the shallow seas at that time and sheltered puddles where seas met rocky shore, protected from UV rays. ....

That's "Where". And it is problematic, bearing in mind that ~4.0 mya, LHB giant impacts would have sterilised the crust up to a kilometre deep and sterilised the ocean. There is also the problems of condensation reactions in watery environments and an oceanic soup would be too dilute. See my that

>Because of gamma radiation, UV and wild temperature swings, only rapidly reproducing self-replicating strands possible, containing backup DNA files for self-repair when damaged by radiation or UV -- until Earth cools off radioactively within the next few billion years (as of 4 bya).

That's *what*, not "how".

There is BTW no such thing as "self-replicating strands" of DNA (or RNA). They each require enzymes and ribosomes to self-replicate. There is also no evidence that a DNA/RNA + enzymes + ribosomes self-replicating system could exist outside a cell. And the cell walls, like the enzymes and ribosomes, are coded into DNA.

You still need to explain "*how* first life emerged on Earth" and "life" is a self-feeding, self-repairing, self-replicating *cell*, with a *minimum* of ~1,500+ gene products (DNA/RNA, ribosomes, enzymes and proteins). See my posts "The Minimal Cell" 1/2 [http://tinyurl.com/o3prh] and 2/2 [http://tinyurl.com/nm6dx].

>That's the reason why there was no evolution beyond single cells until 583 million years ago or so with emergence of Ediacara biota and some 40 million years later with the Cambrian explosion of life.

There are tracks, burrows and coprolite evidence of "bilaterally symmetrical, worm-like animals with a mouth-anus digestive tract" ~600 mya, i.e. ~ 70 mya before the Cambrian Explosion (533-525 mya), as per my Animal Physiology assignment (which one of these days I will post to my blog):

"However, undisputed trails and burrows have been found extending back to 550 Ma (Erwin & Davidson, 2002; Knoll & Carroll, 1999). Fossilised faecal pellets have also been found ~600 Ma (Knight, 1997). These trace fossils were evidently made by bilaterally symmetrical, worm-like animals with a mouth-anus digestive tract (Carroll, 2000)." (Stephen E. Jones, "The Cambrian Evolution of Animal Body Plans," 1 November 2004)

These "worm-like animals with a mouth-anus digestive tract" presumably were triploblastic (three basic body tissue layers) and therefore do not appear to be ancestral to the diploblastic (two basic body tissue layers) "Ediacara biota" (except maybe for some like Dickinsonia [http://tinyurl.com/lbcaa]), but they presumably were ancestral to the Cambrian explosion animals which were triploblastic.

[....]

>Have a good day!

Same to you.

Stephen E. Jones

John Umana said...

Steve, finally somebody my age interested in many of the same subjects. Thanks for your thoughtful and highly informative comments on my piece on Astrobiology. I assume you taught once? (Didn't see much in your Profile.)

I suppose we cannot agree on the question of life elsewhere (though you reserve as to Mars). But I submit to you that something extremely significant is going on with the crop circles being created each year all over the globe. Some of these, sure enough, are fakes. But some are real -- that is, they are not being created by human pranksters, and they cannot be ignored. I've been in touch with the scientists investigating these pictograms, BLT Research, out of Cambridge Massachusetts. I've written some of this up at: http://drumana.blogspot.com/

If you're interested, I've just published a book on the evolution debate from the creationist (or ID)side of the spectrum, seeking to reconcile aspects of Darwinism with creationism. I firmly believe though that science is our best hope of achieving the truth about these matters, but also believe that science teaches us a hellova lot more about these fundamental questions than some scientists have recognized. My book is called Creation: Towards a Theory of All Things. It's on booksurge.com or amazon.com. http://www.booksurge.com/author.php3?accountID=GPUB02608&affiliateID=A000932

Again, thanks for taking the time to share your insights and comments.
Regards,
John Umana
Washington, DC
jumanabeth@aol.com

Stephen E. Jones said...

John Umana said...

>Steve, finally somebody my age interested in many of the same subjects. Thanks for your thoughtful and highly informative comments on my piece on Astrobiology. I assume you taught once? (Didn't see much in your Profile.)

No, I never was a teacher. My day job was a Hospital Administrator. But I am now retired (or rather have a new career as an author, writing a book, "Problems of Evolution" [http://tinyurl.com/bw24m]).

>... But I submit to you that something extremely significant is going on with the crop circles being created each year all over the globe. Some of these, sure enough, are fakes. But some are real -- that is, they are not being created by human pranksters, and they cannot be ignored. I've been in touch with the scientists investigating these pictograms, BLT Research, out of Cambridge Massachusetts. [...]

Crop circles are a good example of the inference to design, based on our universal experience that there is a limit to what unintelligent processes (chance and law) can so.

Once design in reliably detected, there are only two main possibilities: 1) designer(s) within nature; or 2) designer(s) beyond nature. A philosophical naturalist would be unable to consider 2), but as a Christian I am not a philosophical naturalist.

As to 1) there are three sub-possibilities: a) humans; b) time-travellers and c) extraterrestrials.

As to 2) there are three sub-possibilities: a) God; b) angels; c) demons (evil angels); or d) ghosts (spirits of the dead).

I will eliminate 2a) and 2b) because by definition they are good.

I will also eliminate 1b) time-travellers and 1c) extraterrestrials because there is no evidence that they exist and if they did exist I assume they would not waste their time drawing circles in crops.

That leaves 1a) humans, 2c) demons (evil angels) and 2d) ghosts (spirits of the dead).

While there is evidence that there are spirits of the dead (e.g. 1 Sam 28), there is AFAIK no evidence that they can cause physical phenomena. I therefore eliminate 2d) as unlikely.

As for 2c) demons, I consider that a real possibility, given that the Bible indicates that before Jesus returns, there will be an upsurge in demonic activity (Rev 20:1,7-8 [http://tinyurl.com/z8wug]).

However, I still consider 1a) humans, to be the most likely.

I remember (but cannot find the articles on my computer) where a group of pranksters in England in the 1990's owned up to having caused many elaborate crop circles. They even showed how they did it. But many hard-core aliens crop-circle believers refused to accept this.

But I did find on my computer a BBC article [http://tinyurl.com/j7u2e] relating how when Britain had foot-and-mouth disease restrictions on country road movement, crop circles declined markedly, and then when the restrictions were lifted, crop circles returned!

Stephen E. Jones