Blood Flow Requires a Complex, Well-Designed System

Editor's note: Physicians have a special place among the thinkers who have elaborated the argument for intelligent design. Perhaps that's because, more than evolutionary biologists, they are familiar with the challenges of maintaining a functioning complex system, the human body. With that in mind, Evolution News & Views is delighted to present this series, "The Designed Body." For the complete series, see here. Dr. Glicksman practices palliative medicine for a hospice organization.

The cells that make up the organs and tissues of the body require the blood in the circulation to give them what they need so they can do what they need to do. The heart must pump enough blood with enough pressure behind it to maintain sufficient blood flow. Blood flow can be defined as the volume of blood that passes a given point in the circulation system within a given amount of time, and is usually measured in "milliliters per minute" (mL/min).

As I've shown in prior articles in this series, the laws of nature state that blood flow (Q) to a given organ is directly related to the pressure (P) of the blood as it enters its capillaries and inversely related to the vascular resistance (R) applied by its arterioles. This natural relationship can be expressed as Q = P/R. The higher the pressure, the more blood flow and the lower the pressure, the less blood flow. And the higher the vascular resistance, the less blood flow, and the lower the vascular resistance, the more blood flow.

Common sense tells us that the wider the passageway the easier the flow. Just consider rush hour traffic moving along a highway. The more lanes there are available, the more cars can move through in a given amount of time. Now think about what happens when the cars leave the highway. Compared to a single-lane exit ramp, a double-lane one provides much less resistance and allows easier flow off the highway. The blood hurtling through the smaller arteries, trying to enter the arterioles on the way to the tissues, is like cars in a crush of rush hour traffic trying to enter the various exit ramps to reach their destinations. The wider the opening in the arterioles, the more blood can flow through, and the narrower the opening, the less blood can flow through.

The arterioles can increase or decrease the amount of resistance they apply to the blood trying to enter an organ by increasing or decreasing the contraction of the muscle surrounding them. An increase in muscle contraction closes down the opening in the arteriole, making the passageway (lumen) smaller. This increases the resistance and lowers the blood flow. And a decrease in muscle contraction opens up the lumen, decreasing the resistance and increasing the blood flow. In fact, the laws of nature state that the change in blood flow is directly related to the fourth power of the change in the luminal diameter. This means that if the luminal diameter of the blood vessel doubles, the blood flow increases by a factor of sixteen, and if it halves it decreases by a factor of sixteen.

At rest, total blood flow within the systemic circulation (cardiac output) is about 5,000 mL/min (5 L/min). With high levels of activity, something our earliest ancestors would have had to do often, it rises to about 25L/min. However, just because the body can generate enough cardiac output to meet its metabolic needs doesn't mean that the increase in blood flow will automatically go to the organs and tissues that really need it. This requires the body to take control in order to follow the rules that nature throws at it. Real numbers have real consequences, and if with increased activity the body can't get enough blood flow to the heart and skeletal muscle while preserving it to the brain, the body cannot function. This is what the body of our earliest ancestors would have had to have been able to do to survive within the laws of nature, something that evolutionary biology has yet to even mention, never mind explain.

The blood flow to a given organ or tissue is dependent, not only on its mass, but also its energy needs, in other words, what it's doing. The brain of a 70 Kg man has a mass of only 1500 gm, about 2 percent of his total mass. But at rest, the brain receives 750 mL/min, or 15 percent of the cardiac output. The brain needs a high amount of blood flow, over and above what one would expect for its size, because even though the body may be at rest, the brain is always working hard. In fact, no matter how little or how much the body exerts itself, the amount of blood flow to the brain must stay at 750 mL/min for it to work properly. The heart, with a mass of only about 300 gm, less than 1 percent of the body's total, is another organ that must constantly work, even when the body is at rest. At rest, the heart receives about 250 mL/min of the cardiac output, or about 5 percent of the total blood flow.

In contrast, the skeletal muscle, with a mass of about 30 Kg, or 40 percent of the body's total, at rest receives only 15 percent of the cardiac output, or 750 mL/min. At rest, the remaining blood flow mostly goes to the liver and gastrointestinal system (25 percent), the kidneys (20 percent), the fat (5 percent), the bones (5 percent), the skin (5 percent), and the lungs (2.5 percent).

The muscles surrounding the arterioles respond to several different factors. Some of these are intrinsic to what is going on inside and around the arterioles. This includes the pressure the blood applies as it enters and stretches the arteriolar wall and the presence of certain chemicals related to the metabolism of the tissues. Other factors are extrinsic to the arterioles, which include various hormones released by glands and neurohormones released by nerve cells. At rest, the main extrinsic factor that affects local blood flow is the sympathetic nervous system.

Except for in the brain, the sympathetic neurohormone, norepinephrine, attaches to specific receptors on the muscles surrounding most of the arterioles in the body and tells them to stay contracted. The resulting vasoconstriction causes limited blood flow through most of the organs and tissues. At rest, particularly in the brain and the heart, the main intrinsic factor that affects blood flow is autoregulation, in which the arteriolar resistance is constantly adjusted to match the pressure of the entering blood to maintain a relatively constant blood flow.

When the body is very active, such as when our ancient ancestors were running to find food or trying to avoid becoming food, the cardiac output is about 25L/min. The majority of this quintupling of blood flow must go to the skeletal and heart muscle so the body can do what it needs to do to survive. In fact, compared to what it receives at rest, during extreme physical exertion, the amount of blood flow to the skeletal muscle increases 28-fold to about 21 L/min and the blood flow to the heart muscle more than quadruples, going from 250 mL/min at rest, to over 1,000 mL/min. The brain is able to maintain its usual blood flow of 750 mL/min, but most of the other organs and tissues of the body see a decrease in blood flow.

For example, the blood flow to the liver and gastrointestinal system drops about 60 percent, from 1.25 L/min to 500 mL/min and the blood flow to the kidneys drops 75 percent, from 1,000 mL/min to only 250 mL/min. Since the change in blood flow is directly related to the fourth power of the change in the luminal diameter this means that the luminal diameter of the arterioles supplying blood to the skeletal muscle must increase by 130 percent and those to the heart muscle by 40 percent. Those to the liver, the gastrointestinal system and the kidneys decrease by about 10 percent. So, how does the body know when to make these changes?

When the body becomes active the main intrinsic factor that affects local blood flow is something called metabolic or functional hyperemia. Increased muscle activity causes the local buildup of several different chemicals that make the muscles surrounding the local arterioles relax. This vasodilation reduces the vascular resistance and increases local blood flow. This is one of the main reasons why the blood flow to the skeletal and heart muscle increases with activity.

In addition, the main extrinsic factor that affects local blood flow with increased activity is an increase in the sympathetic response as well, but with an added twist. Except for the brain, an increase in norepinephrine usually makes the muscles surrounding the arterioles everywhere else in the body contract. This causes an increased vascular resistance and less blood flow. This explains why, with increased physical activity, the blood flow to most of the other organs and tissues is reduced. But with increased activity, more epinephrine is released as well. The muscles surrounding the arterioles that supply blood to the skeletal and heart muscle are unique in that they have specific receptors for epinephrine. Epinephrine stimulates these muscles to relax, reversing the effects of norepinephrine, which reduces the vascular resistance and increases the blood flow to the skeletal and heart muscle.

We have seen that to survive under the laws of nature, the body must follow the rules and take control by making sure that, when it comes to blood flow to specific organs and tissues, the numbers follow the Goldilocks principle and be "just right." Having all the parts in place to maintain this type of control requires, not only that the system be irreducibly complex, but also have anatural survival capacity to be able to do exactly what has to be done and at the right time. In fact, to do all of this the body must inherently know that Q = P/R and the change in Q is directly related to the fourth power of the change in the luminal diameter.

This completes our discussion of cardiovascular function and how the body makes sure that its trillions of cells get what they need to live, grow, and work properly. However, life is a dynamic process and our earliest ancestors would have had to have remained very active to win the battle for survival. The body does not live within the imaginations of evolutionary biologists but within the laws of nature in which battles involves injuries. Injury to blood vessels leads to bleeding, which if serious enough can be fatal. That's what we'll start to look at next time.

Read original article HERE

Archaeological Find: A Testament to God's Work Throughout History

The first reference to the city of Gath in the Bible occurs in the book of Joshua. In chapter 11 we’re told that there were no Anakim, a race of giants, left in Israelite territory except for a few in Gaza, Gath, and Ashdod.

The next time we hear of Gath is in connection with one of those giants, Goliath, in I Samuel 17. From then on, Gath becomes the most-mentioned Philistine city in the Bible. In I Chronicles 18, David captures the city. In II Chronicles 11, his grandson Rehoboam fortifies it. The city was later captured by King Hazael of Damascus and then recaptured by King Uzziah, whose death figured in the vision of Isaiah 6.

Yet until recently, no one was sure exactly where Gath was located. It wasn’t so much that they doubted its existence as they couldn’t find it.

But now it appears they have.

Israeli archaeologists, digging at a site about 20 miles northwest of Hebron, found what is being described as a “massive gate” that marked the entrance to what was then the region’s largest city.

The gates aren’t the only impressive thing about what they’ve found. According to team leader Aren Maier, based on what they’ve dug up so far, the city’s walls and other fortifications were so formidable that they “formed a rather imposing boundary that prevented the Kingdom of Judah from expanding westward.”

Thus, we have evidence of the more or less constant conflict between the people of Israel and their Philistine neighbors. It took the greatest warrior of the Bible, King David, to overcome that “rather imposing boundary.”

And Maier’s team found more than fortifications. They also found the remains of a temple that, like Gath itself, changed hands several times. Interestingly, after the Philistines captured it from the Israelites, they not only destroyed it, they desecrated it by using it as a livestock pen. It’s a testimony in stone to the enmity between those two peoples as described in the Bible.

And it’s not the only such testimony in stone. A few years ago Eric Metaxas told our BreakPoint listeners about a find in the Valley of Sorek, which marked the ancient boundary between Israelite and Philistine territories and where the Bible tells us that Samson met Delilah.

The Philistine side was littered with pig bones, while there were none on the Israelite side. And so it’s reasonable to see that as “evidence of the Israelites’ sense of being set apart from their pagan neighbors.”

It’s reasonable because biblical faith is an historical faith. The accounts in the scripture do not take place in some mythical time-before-time like that of their pagan neighbors or the Bhagavad Gita in Hinduism.

They are stories about God and His servants—and enemies—working in human history in furtherance of a divine purpose whose culmination will also occur in human history. When John tells us that the “Word became flesh and pitched his tent among us”—the Greek verb there comes from the Greek word for “tent”—he was referring to Tent of Meeting in Exodus 27, where God met his people.

In entering time and place, as described over and over in the Scriptures, most significantly in Christ Jesus, God has hallowed human history. He made it the setting in which His salvific activity would take place. Thus it shouldn’t come as a surprise when finds like the one I just told you about occur. Activities in history, even seemingly insignificant ones, often leave traces.

But of course there’s nothing insignificant about Israel’s story. After all, it’s that story of the people whom God chose to use in order to repair all that human sin had broken, culminating in the sending of his Son, who—as the Apostle John reports—promises to “make all things new.”

And as Gath and its great hero found out at the young hands of Israel’s future king, that’s something that no barrier, no matter how imposing, can get in the way of.

Click HERE for original article

Doctors and Evolution

David Klinghoffer

In an almost charmingly naïve article, Francie Diep at Pacific Standardwonders, "Why Do Some Doctors Reject Evolution?" Her news peg is Republican presidential hopeful Ben Carson, a neurosurgeon who has expressed reservations about Darwinian accounts of evolution -- though I don't know that anyone has questioned him sharply and in an informed way about his ideas on the subject.

Miss Diep is perplexed: "We assumed such beliefs would be unusual among doctors." Not so, she discovered.

[W]hen Pacific Standard talked to doctors, many didn't find their colleagues' rejection of evolution unusual. "Nope, it's not uncommon at all," says David Gorski, a surgeon and researcher at Wayne State University. Even in the national spotlight, Carson isn't the only high-profile politician-physician to doubt the well-established biology concept.

All of the physicians Pacific Standard talked with, both on and off the record, had the same answer to "How is it possible?": Although doctors use many insights from biology, many don't actually need to understand or believe in evolution correctly to do their jobs.

"Most physicians are not scientists. This is not a knock, but they're more akin to engineers," Gorski says. "They take science that's already known and they apply it to a problem, the problem being making patients better."

It's not a knock? It sure sounds like one. The countervailing consideration is that physicians and engineers -- and why not throw in computer scientists as well? -- do something on a daily basis that evolutionary biologists never do. The doctor or engineer's responsibility is to maintain, devise, or build complex systems, even from the ground up, systems that must operate continuously without fail. If the system does fail, then the physician, engineer, or computer scientist has flopped in his job. Not uncommonly, the results of such a flop can be fatal -- for the patient on the operating table, for example, or the passenger in the jet airplane.

Luxuriously insulated from reality, biologists theorizing about the history of life, how it arose and developed, face no such pressure to fill in what Ann Gauger calls the "white spaces" in evolutionary thinking. (For more on that, see "The Modesty Chronicles.") Vague stories and magic words typically substitute for detailed explanations of how biological systems could come into being through purposeless, unintelligent processes alone. It often seems that the only serious pressure that Darwinists do face is from us.

Miss Diep rolls out the usual line about how evolution is vital to biology which is vital to medicine, ergo medicine needs evolution or ought to do so. But even some hardline Darwinists admit that the practical benefits of their cherished theory are scarce.

Coincidentally, a correspondent today sends across my desk this from biologist Jerry Coyne, of Why Evolution Is True fame. Writing in Nature ("Selling Darwin"), Coyne has conceded:

[T]ruth be told, evolution hasn't yielded many practical or commercial benefits. Yes, bacteria evolve drug resistance, and yes, we must take countermeasures, but beyond that there is not much to say. Evolution cannot help us predict what new vaccines to manufacture because microbes evolve unpredictably. But hasn't evolution helped guide animal and plant breeding? Not very much. Most improvement in crop plants and animals occurred long before we knew anything about evolution, and came about by people following the genetic principle of 'like begets like'. Even now, as its practitioners admit, the field of quantitative genetics has been of little value in helping improve varieties. Future advances will almost certainly come from transgenics, which is not based on evolution at all.

He wrote that in 2006 -- maybe he'd be more circumspect now. But I'm not aware that anything has changed in medicine or other fields to shift a reasonable person from such a view.

Coyne, of course, believes that the importance of evolution lies in its power to explain, or explain away, not to heal or otherwise improve the quality of our lives. It's precisely that explanatory power, as we know, that is most urgently in need of critical examination.

Read original article HERE      

When the Dust Settles

Christians don’t have only statements and creeds on which to stand. We stand on holy ground, before a holy God. And as Moses, Daniel, Mary, Zechariah, Elizabeth, and countless others have discovered, it is a place of both awe and intimacy before the very One who describes and makes sense of all reality.

I would like to begin by telling a story about an event that took place some years ago when I was beginning my studies, an event that has had a major impact on my life and my approach to engaging others to this day. I had a neighbor who was deeply committed to a version of the New Age movement. He and I had many conversations about God in the course of several months. He was a highly educated man with a couple of PhDs to his name, and so he provided me with an opportunity to test my training. But the training I was receiving in apologetics was good, and I soon realized that I could not only answer the questions he was asking about my faith in God, I could also poke holes in his worldview in a way that forced him to check books out of the local library to try and put his worldview back together. And I was feeling very good about myself. I was actually getting it!

Finally I decided to challenge him to consider giving his life to Christ. His reaction surprised me. He did not seem to care at all about what I was telling him. So I said to him, “Can you please explain to me what is going on? You don’t seem to care about what I am telling you.” His answer was even more baffling to me. He said to me, “Listening to you asking me to become a Christian is like listening to a naturalist asking me to become a naturalist.”

I said to him, “What in the world do you mean? I just asked you to consider giving your life to the God who created you, and you are accusing me of being an atheist? What do you mean?”

He said to me, “All you Christians have are statements and creeds. You think that if people accept those statements and creeds, everything will be okay. When I pray, I get in touch with powers that you know nothing about.”

And that was one of the most convicting things anyone has ever said to me. Because what this man was saying to me was essentially this: “Yes, you can say a lot of very convincing things about your faith, but does your faith really rise beyond well-argued propositions?”

In his book Beyond Opinion, Ravi Zacharias says that the greatest obstacle to the reception of the gospel is not its inability to provide answers; rather, it is the failure on the part of Christians to live it out. J.I. Packer writes similarly in his classic book entitled Knowing God:

From current Christian publications you might think that the most vital issue for any real or would-be Christian in the world today is church union, or social witness, or dialogue with other Christians and other faiths, or refuting this or that -ism, or developing a Christian philosophy and culture…. [It] is tragic that … so many in our day seem to have been distracted from what was, is, and always will be the true priority for every human being—that is, learning to know God in Christ.1

Whatever your position of faith, it is helpful to occasionally step back and ask a similar question of priority. Whatever your calling in life, what is the ultimate goal of all that you do? As Jesus wisely observed, “Where your treasure is, there your heart will be also” (Matthew 6:21).

Indeed, the Bible addresses this question in many places, in both the Old and New Testaments, but none so much as in the person of Christ himself. If there is a message we hear loudest in his coming to earth it is this: the primary call of God is to know God, to be near God, not to argue on God’s behalf. The end is knowing God. Even the Scriptures were given to us as a means to that end. For when all is said and done, when the dust settles, it is the eternally incarnate Son of God who lies behind the hauntingly inescapable question, “Who do you say that I am?” It is a question each of us must answer, with our words and with our lives. There is no neutral ground.

No, Christians don’t have only statements and creeds on which to stand. We stand on holy ground, before a holy God. And as Moses, Daniel, Mary, Zechariah, Elizabeth, and countless others have discovered, it is a place of both awe and intimacy before the very One who describes and makes sense of all reality. How wonderful it is when the curtain is pulled back, and we see God for who God truly is, and we are able to say with Peter, “You are the Christ, the Son of the living God.”


John Njoroge is a member of the speaking team at Ravi Zacharias International Ministries in Atlanta, Georgia.

1J.I. Packer, Knowing God (Downers Grove, IL: InterVarsity Press, 1993), 279.

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Question on Time amd the Origin of the Universe


Questions on Time and the Origin of the Universe

Dr. Craig,

My name is Tejas and I'm 13 years old. I admire you and have watched many of your debates. I sincerely request you to answer this question, and thank you for taking your time to read this.

My question regards the Kalam Cosmological Argument, that I have seen you present in some debates. The first part is, is the initial premise on causation refuted if the zero-energy universe hypothesis is true, and what would be the flaws if the universe were a vacuum fluctuation? And regarding the second premise, could you please tell me why you think the presentism ontology of time is true?

I thank you so much and apologize if there seems to be any disrespect in the question. Please do answer this question.

Thanks so much,

Warm regards,


Click HERE to read Dr. Craig's answer


Chimps Can Cook! -- Or Not

We are continually told: "Humans are not exceptional!" Scientists and advocates huff and puff to show how animals are just like us, and the media eats it up.

This one made me laugh. The other day, the Guardian ran an article with a title that declared chimpanzees can cook. The title, however, ended up being a bit misleading:


A study found that chimpanzees prefer the taste of cooked food, can defer gratification while waiting for it and even choose to hoard raw vegetables if they know they will have the chance to cook them later on.


The findings suggest that our earliest ancestors may have developed a taste for roast vegetables and grilled meat earlier than previously thought, potentially shifting the timeline for one of the critical transitions in human history.

Wow! So, given the chance, they cook? Well, not exactly. They just exchanged raw food for better tasting cooked food:

For safety reasons, this was a plastic lunchbox with a false bottom, which researchers used to "transform" raw sweet potato placed inside by the chimpanzees into a cooked slice of a similar size...

Overall, the apes chose cooked potato nearly 90% of the time when they were given a straight choice and they were nearly as keen when they had to wait one minute while it was "cooked" by the researcher (who shook the plastic box ten times).

The chimps continued to opt for the cooked option 60% of the time when they had to carry the food some distance in order to place it in the "oven" -- although since they often carried it in their mouths this was a challenge and they sometimes appeared to eat the food on the way, "almost by accident".

So, chimps don't cook. Nor is there any evidence they have ever tried. They reacted to an unnatural situation set up by humans. But, of course, this means chimps are people too, or perhaps better stated, we are just chimps:


Dr. Erica van de Waal, a psychologist at the University of St Andrews, said the findings add to the growing list of parallels that have been observed between human and ape behaviours. "The more we study our primate cousins, the more we realise that they have the bases of most of our cognitive abilities, including for language, culture and fairness," she said.


Other than the fact that they don't have the actual abilities.

The experiments were performed at the Jane Goodall Institute's Tchimpounga Chimpanzee Sanctuary, which may shed some light on the results. Goodall is an ideologue as much as a scientist and exaggerated the inner lives of the chimps she observed to make them seem more human.

Read original article HERE

Is Worship of Jesus Idolatry?

Hello Dr. Craig,

First, I want to thank you for all that you have done for the cause of Christ. You have been a powerful witness for the faith. I've continually been challenged in my thinking and knowledge by your writings and public discourses. You have taught me how to think critically and how to share Christian truth in a Christ-like manner.

I am a student of philosophy looking to go into apologetics ministry. In my studies and my time witnessing I've had to address many of the common objections to Christianity. One of the more recent objections has come from a Jewish man that I am witnessing to. It seems that one of the crucial things that is holding him back is the worship of Jesus. He couldn't see any way how this wouldn't end up being idolatry because, as he claimed, “you would be worshiping man rather than God”. Of course, I tried to point out that Jesus has two natures but it seems like this point was missed. Do you have any helpful ways to explain our worship of Jesus in a way that bypasses this objection? How should we understand our worship of Jesus? Do we worship him in deity and merely admire his humanity?

Any of your thoughts on this issue would be greatly appreciated! Thank you for all that you do in the name of Christ.


United States

To read Dr. Craig's answer please click HERE

The Reliability of the Gospels

Dear Dr. Craig,

First off, I want to thank you for all that you have done for me through your ministry and hope that your reach continues to spread. I grew up in a conservative Christian home and for the most part accepted everything that I had been taught. Then during my junior year of high school I read some Richard Dawkins, and the likes, and quickly lost my faith. About six or so months later I discovered your ministry and my life was changed! Your arguments convinced me and in no time I had gone back to my faith. I read On Guard and Reasonable Faith among other Christian authors as well. I felt that my faith was strong and I even considered changing my major to Philosophy for a short time. But now, I am saddened to say that I am slowly losing my faith in the Christian God.

Before I go into my reasons for losing my faith, I want to point out that at this point I still believe that Christ rose from the dead but if I were to give that up I would comfortably sit in a deist position, being that I consider arguments for a Gods existence to be convincing. So, the reason for my diminishing faith is that I have found that I can no longer trust the Old or New Testament. I will leave the Old Testament aside for now and focus on the new. In your books you have maintained that the earliest gospel was Mark and that it was written some 40 years after the death of Jesus, give or take a few years. You also hold that in the time between the event of Jesus' death and the writing of the Gospel of Mark that legends could not have infiltrated the original narrative because 40 years is not long enough. I find this reasoning very problematic.

I could grant you that the resurrection did happen (which I hold to) due to its attestation in multiple gospels and the Pauline epistles but that would in now way confirm any of the stories or teachings of Jesus. His whole life could have been made up by the writers, not due to them being corrupt but that these were the simply the stories they were told of Jesus that were passed on to the early Christians. My question here is how can we trust any of the stories of Jesus if they are not attested in each of the synoptic gospels?

I also find that the explanation that 4o years is too small of a window for legend to become present hard to buy into. First, within 4o years it is likely that few if any of the original eyewitnesses were alive being that the lifespan of humans then was minimal. So how could the stories be checked for accuracy if the eyewitnesses themselves were no longer around to do so? Secondly, when the eyewitnesses went to tell their story so others would follow Jesus they could not have told every single person from every town, therefore relying on the ones they told to pass on the story. It is plausible to think that if one's wife wasn't convinced by the stories of Jesus that the eyewitnesses told her husband then her husband would make up an even more miraculous story, like Jesus turning water into wine, to get her to believe. This is just one scenario of many that very likely took place leading to multiple if not the majority of Jesus' life being composed of stories that were made up to convince others.

Now as I stated earlier, I am a Christian but it is becoming increasingly difficult to hold the New Testament as authoritative concerning the matters of Jesus' life.

Best Regards,



United States

To read Dr. Graig's answer please clck HERE

Warm-Bloodedness is an Ocean Fish Stuns Evolutionists

It's a big, round fish called the opah, found in deep waters around the earth and looking a bit like someone's goldfish that seriously outgrew its bowl. Some fish, like tuna and sharks, can control temperature in parts of the body. This one can keep its whole body warm, giving it improved performance in the coldness of the depths. It's the first example of whole-body endothermy in a fish, raising new questions about the evolution of a complex trait.

The story caught the attention of many news sites, such as the BBC News and the Washington PostThe Weather Channel featured a short news video and report, saying that warm-bloodedness gives this fish a competitive advantage when it hunts slower, cold-blooded prey. Nate Scott at USA Today got a little crazy with his coverage, saying "Scientists have found a warm-blooded fish and we're probably all dead... They're evolving."

This is a sign. This is a message from the deep. Fish are changing. They're getting smarter. It won't be long before the warm blood of this fish starts burning hot, hot with a desire to eat us one by one.

Or perhaps not. Let's take a look at this nice harmless fish scientifically. Calling it "warm-blooded" is a bit of a misnomer, since it lacks the tightly regulated endothermic homeostasis seen in higher vertebrates like mammals and birds. Instead, as Sacha Vignieri explains in a short statement in This Week in Science, the opah distributes heat around its body that's generated by its swimming muscles.

Mammals and birds warm their entire bodies above the ambient temperature. Generally, this ability is lacking in other vertebrates,although some highly active fish can temporarily warm their swim muscles. Wegner et al. show that the opah, a large deepwater fish, can generate heat with its swim muscles and use this heat to warm both its heart and brain. This ability increases its metabolic function in cold deep waters, which will help the fish compete with other, colder-blooded species. [Emphasis added.]

Conservation of muscle heat is not that unusual. As noted, tuna and some sharks can warm parts of their body with it. The source paper in Scienceidentifies the key to the mechanism in the opah: counter-current heat exchangers in the gills.

Here, we describe a whole-body form of endothermy in a fish, the opah (Lampris guttatus), that produces heat through the constant "flapping" of wing-like pectoral fins and minimizes heat lossthrough a series of counter-current heat exchangers within its gills. Unlike other fish, opah distribute warmed blood throughout the body, including to the heart, enhancing physiological performance and buffering internal organ function while foraging in the cold, nutrient-rich waters below the ocean thermocline.

Counter-current heat exchangers (CCHE) are common in vertebrates. We have them in our kidneys. Similar mechanisms are found in sea turtles, foxes, and dolphins. Illustra Media's new film Living Waters (to be completed this month) will illustrate a particularly amazing example of a CCHE in humpback whales that creates a severe challenge for Darwinian evolution.

Other fish have CCHE's, too, so it's not overly surprising that the opah can use the mechanism to distribute heat generated by its fin muscles to warm itself. This does not, however, minimize the wonder of a CCHE. It is achieved by a "wonderful net" of blood vessels (rete mirabile, literally "miraculous web" in Latin) that provides an ingenious method to regulate core body temperature.

In a rete (plural: retia), arteries and veins mesh into networks of fine vessels that flow in opposite directions, as the term counter-current implies. This allows heat to diffuse from warm arteries to cold veins. In dolphins, excess heat from swimming is shed to the environment through retia in the dorsal fin and tail, where the blubber layer is absent.

The opah has retia in its gills. The authors explain how this provides warm-bloodedness in an unusual way for a fish:

What is exceptional about the opah is its arrangement of counter-current retia mirabilia located inside each thick, fat-insulated gill arch (Fig. 2), which thermally isolate the respiratory exchange surfaces from the rest of the body. Vascular casts of the gills (Fig. 2, A, C, and E) reveal that unlike other fishes, extensions of the afferent and efferent filament arteries (which deliver and collect blood immediately pre- and post-gas exchange at the gill lamellae) are embedded within each gill arch in a tightly bundled and contorted manner to form an arterio-arterial rete. Specifically, the afferent and efferent arteries of each individual filament are closely coupled (Fig. 2E) and stacked in an alternating pattern within the arch (Fig. 2, C and D) so that the cold oxygenated blood of each efferent vessel (returning from the respiratory exchange surfaces) should be warmed by the conduction of heat from the warm deoxygenated blood in the afferent filament arteries on either side (which are carrying blood to the gas exchange surfaces). As a result,oxygenated blood leaving the respiratory exchange surfaces should be warmed before entering into efferent branchial arteries for distribution to the rest of the body.

These retia, in other words, are unusual in that they are all composed of arteries, not arteries and veins. Heat from the warmer deoxygenated blood is transferred to oxygenated blood in the gills, so that it is not lost to the ocean water. But even that is not enough to keep the fish's brain warm. The authors found an additional rete in the muscles that move the eyes that adds a littlemore heat to the cranium. This way, the fish can avoid the mental sluggishness of a cold brain.

"Of particular importance is the capacity of opah to increase the temperature of the heart," they continue, by conserving body heat with specialized fat layers. The combined systems work well for a fish that spends most of its time below the thermocline in the frigid waters of the deep. "With a warm body core and heart, and even warmer cranial region, opah have the capacity for enhanced physiological function in their deep, cold habitat."

In short, the opah employs specialized adaptations of traits that are present in other fish. They are arranged in ways to conserve and channel heat for this species' deep-water needs. Consequently, the fish can call the world's deep oceans home.

And Now, Evolution

What do the authors say about how these adaptations evolved? Not much.

This study presents morphological, temperature, and behavioral data that demonstrate an independent evolution of a more whole-body form of endothermy present in the opah, Lampris gutattus -- a poorly studied, large, mesopelagic fish with a circumglobal distribution....

In many respects, the opah has converged with regionally endothermic fishes such as tunas and lamnid sharks for increased aerobic capacity. However, unlike these active, more surface-oriented predators that are thought to be derived from tropical ancestors and to use regional endothermy to expand their thermal tolerance or habitat utilization into deep and colder waters, the opah's evolutionary history is likely tied to greater oceanic depths, with all but the most basal lineage of the Lampridiformes inhabiting the mesopelagic zone (200 to 1000 m depth). Therefore, rather than using regional endothermy to dive below the thermocline during temporary forages, the opah (with its more whole-body form of endothermy) is distinctively specialized to exploit cold, deeper waters while maintaining elevated levels of physiological performance. The discovery of this form of endothermy, coupled with the recent finding of several distinct opah species inhabiting different regions of the world's oceans (including the subpolar southern opah, L. immaculatus), sets the stage for future comparative studies to further explore this key evolutionary innovation.

The explanation? Convergent evolution to the rescue! This fish's evolutionary history is tied to the depths. Give us more funding, and we can "further explore this key evolutionary innovation."

If that leaves you feeling unsatisfied, consider intelligence as a cause. Intelligence can take a solution that works in one environment and apply it in different animals in different environments. A rete mirabile is a complex system that cannot arise in a gradual, stepwise manner, because all the parts have to function together before any part has survival value. "Convergence" and "innovation" are magic words that provide no understanding. But since we know of a cause -- intelligence -- that can adapt a similar solution in multiple ways, that is a cause that a rational scientist should pursue.