Is Our Sin Nature Embedded in Our Mammal Nature?

Consider the parallels in the long table in this post. It reveals who we are. God’s gigantic global project for us humans is to lift us out of our sin nature and recover the image of God in Christ.

There are two theories as to how we have our sin nature. One is that it is imputed to us from Adam, by virtue of his being our federal head. The second is that it is imparted to us from our parents through genetics, from Adam (or humankind) to now. Sin is in our genes.

This post explores the second theory with additional information.

At the time of this posting, I teach at a community college, and I have found that the best way to help students see a higher vision for their lives is to draw parallels between nonhuman mammals and humans, and then call them to live higher, to develop their souls. Science teaches students that they are mammals, and they will not deny science in favor of a skewed and mistaught version of Christianity that denies the obvious. Nor should they deny science, when it is so clear and correct on this topic. Humans belong in the mammal category. Then, when I spell out for them the numerous parallels, light bulbs in their eyes go off all over the room. They see themselves as they really are. They can change. They can aim higher. They have hope.

In this post, I go further than what I can say in the state-run classroom and discuss the fractured image of God in all of us humans, and how God’s goal is to restore his image in us.

Just take this post for what it is: a tentative, exploratory musing.

If you are a new believer or get easily confused and upset, click out now.

Image of God in humans

The Bible says we are made in God’s image (Gen. 1:26-27; Gen. 9:6).

One more time for emphasis and clarity:

Humans are made in the image of God.

Yet science says and our own experience proves that we are mammals.

We fit the classic definition: “A warm-blooded vertebrate animal of a class that is distinguished by the possession of hair or fur, females that secrete milk for the nourishment of the young, and (typically) the birth of live young” (Source).

1.. All humans are mammals.

2.. You and I are humans.

3.. Therefore, you and I are mammals.

Does Scripture support the fact that we are mammals?

Gen. 2:7 says God formed humankind (’adam) from the dust of the ground, and Gen. 2:18 says God formed all the wild animals and birds out of the ground. Whether you take those two verses literally or figuratively, they teach that humans and mammals are made of the same substance.

The Hebrew noun zakar (pronounced zah-kahr) means “male” in contrast to the generic “man” (used 82 times). It can refer to male offspring of humans (Lev. 12:2; Is. 66:7; Jer. 20:15) and animals (Exod. 12:5; Lev. 1:3, 10; 22:19).

The Hebrew noun for soul or life or consciousness is nephesh (used 757 times), and both animals and humans can have it (Gen. 1:20-21, 24, 30;  2:7, 19; 9:4, 10, 12, 15, 16). Even the Revelation says that creatures of the sea have “life” (Rev. 8:8; 16:13).

The psalmist sees himself as a brute beast, when he had lacked wisdom: “I was senseless and ignorant; I was a brute beast before you” (Ps. 73:22)

When the wise man Agur thought he lacked human understanding, he described himself in this way: “Surely I am only a brute, not a man; I do not have human understanding” (Prov. 30:2).

In Solomon’s opinion, he wrote: “As for humans, God tests them so that they may see that they are like the animals” (Eccl. 3:18).

Jeremiah compares the lust in humans with the “lust” in horses: “They are well-fed, lusty stallions, each neighing for another man’s wife” (Jer. 5:8; 13:27).

Paul warned Titus that Cretans can fall into their baser nature: “One of Crete’s own prophets has said it: “Cretans are always liars, evil brutes, lazy gluttons.” (Titus 1:12)

Peter writes that degraded humans are irrational animals, born with natural instincts: “… They are like unreasoning animals, creatures of instinct, born only to be caught and destroyed, and like animals they too will perish” (2 Pet. 2:12). Then he goes on to compare them to dogs that return to their vomit, and washed sows that go back to wallowing in mud (v. 22).

Jude also says that humans outside of life in the Spirit follow “mere natural instincts”: “and the very things they do understand by instinct—as irrational animals do—will destroy them” (v. 10). And “these are the people who divide you, who follow mere natural instincts and do not have the Spirit” (v. 19)

Scripture often compares human mammals to sheep (Ezek. 34:11-12, 15; Matt. 9:36; 10:6; 18:12-13), but this is metaphorical, so let’s not make too much of this one point.

The Greek word for physical “flesh” is sarx (used 147 times), though there may be differences in the flesh of one mammal to the next (1 Cor. 15:39). In some contexts, it is sometimes translated as “sin nature” because the contexts warrant it (Rom. 6:6:19; 7:5; 18, 25; 8:3-9, 12-13; Gal. 5:16-19). So it could be that the biblical authors saw that the sin nature resides in the flesh, perhaps the brain or the “heart” and body, where our nature is expressed.

The Greek word for “body” is sōma (used 142 times), and it can be used of humans and animals (Jas. 3:3; Matt. 5:29; 6:22; 26:12).

Here is a sample verse that connects the flesh and the body with sin: “For if you live according to the flesh (sarx), you will die, but if by the Spirit you put to death the misdeeds of the body (sōma), you will live” (Rom. 8:13).

Now let’s apply these biblical data.

Parallels between nonhuman and human mammals and God’s higher calling

This table shows the parallels between nonhuman mammals and humans and bad behavior and most importantly how God calls humans to restore his image and follow his higher calling to have souls filled with righteousness.

The clearest and most direct way to change the human condition is biblical revelation, the third column.

Nonhuman Mammals

Human Mammals

God’s Higher Calling

Male chimps in a troop kill a stranger chimp. Some humans, usually males, murder. You shall not murder (Ex. 20:13).
Male troops of chimps wander and threaten and kill other primates. Some humans form gangs and threaten and kill citizens and other gangs. Get rid of all … rage and anger, brawling …  (Eph. 4:31).
Various mammals (and birds) take food that they did not gather or kill. Some humans steal. You shall not steal (Ex. 20:15).
Some females abandon newborn. Some females abandon newborn (and even abort it before birth). I am like a weaned child with its mother; like a weaned child I am content (Ps. 131:2). Though my father and mother forsake me, the LORD will take me up (Ps. 27:10).
A juvenile elephant regularly rampages and kills other animals until reserve wardens put in a big bull, and the juvenile no longer kills or rampages. Some juvenile males rampage without father figures, until fathers come into juveniles’ lives. You love those who hate you and hate those who love you. You have made it clear today that the commanders and their men mean nothing to you. I see that you would be pleased if Absalom were alive today and all of us were dead (2 Sam. 19:6).
A baby monkey throws a fit when it is being weaned. A small child throws a fit because he does not get his way. Folly is bound up in the heart of a child, but the rod of discipline will drive it far away (Prov. 22:15).
Stronger monkeys bully weaker ones. Stronger people bully weaker ones.  “You bully, you! At last you have what was coming to you! (Is. 14:4, NLT). Let the weakling say, “I am strong!”  (Joel 3:10)
Elephants in “Herd “A” kidnap a baby elephant from “Herd B,” and the matriarch and other females of “Herd B” struggle to get it back. Some people kidnap children. If someone is caught kidnapping … the kidnapper must die (Deut. 24:7).
Koko the gorilla, trained to communicate with a human trainer, lied in saying that her kitten damaged items in her enclosure. Some people lie. A wicked person listens to deceitful lips; a liar pays attention to a destructive tongue  (Prov. 14:5).
Male mammals spray and rub to mark territory. Some teen boys spray-paint to mark territory. Ex. 22:1-15 is all about protection of property
Some kill offspring of another family of same species (e.g. wolf kills pups of another wolfpack) Some people kill children. You shall not murder (Ex. 20:13).
Some mammals kill offspring from another male (e.g. lions, taking over a pride, kill cubs of previous males). Some stepparents mistreat and even kill stepchildren. Fathers, do not exasperate your children; instead, bring them up in the training and instruction of the Lord (Eph. 6:4).
Some mammals unmistakably look guilty, like a cowering dog after it killed a chicken. Many people look guilty when they do wrong. The look on their faces testifies against them;… Tell the righteous it will be well with them  (Is. 3:9, 10).
Male gorillas pound chest to show dominance. Some males pound chest to show dominance. … nor is there male and female, for you are all one in Christ Jesus. (Gal. 3:28); you, my brothers and sisters, were called to be free. But do not use your freedom to indulge the flesh; rather, serve one another humbly in love (Gal. 5:13).
Mammals can get addicted to drugs and nicotine and alcohol if fed to them, and they do not know how to stop. Chimps can learn to be chain smokers (and so on). Some people can also get addicted to those things and find it difficult to break the habit. They can become chain smokers (and so on). Do not get drunk on wine, which leads to debauchery. Instead, be filled with the Spirit (Eph. 5:18); older women [are …] not to be … addicted to much wine (Tit. 2:2).
Males and females attract. Males and females attract, can turn into lust. (Attraction is not sinful, but lust is.) But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart (Mt. 5:28).
Some mammals seem to be attracted to same sex. Some people are attracted to same sex. Neither the sexually immoral … nor men who have sex with men … will inherit the kingdom of God … And that is what some of you were. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God (1 Cor. 6:9-10).
Alpha male claims many females. “Alpha” male desires sex with many females; one religion endorses polygamy for rich male, the alpha, the “top dog.” … the husband of one wife … (1 Tim. 3:2, NKJV).
Eager to show they are the alphas, males fight for right to breed. Climbing to top, some males fight (sometimes fist-fight) to show they are alpha male, for right to breed. Jesus called them together and said, “You know that the rulers of the Gentiles lord it over them, and their high officials exercise authority over them. Not so with you. Instead, whoever wants to become great among you must be your servant, and whoever wants to be first must be your slave— just as the Son of Man did not come to be served, but to serve, and to give his life as a ransom for many”  (Mt. 20:25-28).
Some female chimps trade sex for food. Some females sell their bodies for money. Jesus said to them, “Truly I tell you, the tax collectors and the prostitutes are entering the kingdom of God ahead of you. For John came to you to show you the way of righteousness, and you did not believe him, but the tax collectors and the prostitutes did. And even after you saw this, you did not repent and believe him (Mt. 21:31a-32).
Some males rough up females. Some males rough up females. Husbands, love your wives, just as Christ loved the church and gave himself up for her (Eph. 5:25).
Sibling rivalry can get intense. Sibling rivalry can get intense. How wonderful and pleasant it is when brothers live together in harmony! (Ps. 133:1, NLT)
Siblings sometimes fight over food. Young siblings sometimes fight over food. … and all of you are equal as brothers and sisters (Mt. 23:8).
Nonalpha chimps and other nonalpha mammals (wolves, coyotes) cheat on alpha male with nonalpha females claimed by alpha male. Men and women cheat (adultery). You shall not commit adultery.  (Ex. 20:14)
Males are less discriminating in breeding. Males are less discriminating in breeding (males visit brothels much more often than females do, if at all). Should a man take his body, which is part of Christ, and join it to a prostitute? Never! (1 Cor. 6:15, NLT).
Mammals seem to eat almost nonstop. Some people eat too much (gluttony). Do not join those who drink too much wine or gorge themselves on meat, for drunkards and gluttons become poor, and drowsiness clothes them in rags (Prov. 22:20-21).

The above table shows that God’s global project is to lift humans out of their mammal / sin nature and restore his image in them.

Further, our mammal nature may equal human sin nature, in part. At the very least our sin nature is embedded in our mammal nature, in part. If this is true, then it argues for the theology that says that original sin / mammal nature is inherited from human parents to offspring; they pass it along to children. The doctrine of original sin is sustained.

Neutral similarities

Some similarities between nonhuman mammals and human mammals are neutral.

Nonhuman females are attracted to an alpha male; human females are attracted to a human alpha male (an athlete, for example).

Female primate gestures and postures to show sexual availability; woman gestures and postures to show sexual availability.

Nonhuman females discriminate more than males in breeding preferences; human females discriminate more than males in breeding preferences.

Sex hormones influence desire to breed; sex hormones influence desire to breed. (Sex in marriage is not sinful.)

Positive similarities

Some mammals sometimes do good things, like a dog showing loyalty to its owner or the alpha male, the leader of the pack. Dogs have sacrificed their lives to save their human alphas or pack members.

An TV animal documentary about a herd of elk showed that one was wounded, and another one stayed with it and chased off a lone wolf.

So nonhuman mammals and human mammals can do both bad and good actions. That’s why I need to add that our mammal nature is our sin nature in part.

Questions and answers

1.. Does the sinful mammal nature permeate the soul and spirit of a human?

Some teachers claim that the human spirit, when it is born again, remains sinless. However, we are a unit, whether you believe in a body, soul and spirit, or just a body and soul. Sin defiles the whole person.

2.. Do human mammals have souls?

Yes, of course, they do. The Bible affirms it everywhere, as I noted in the Scripture section. And if you believe in three parts of the human (spirit, soul, body), then each human mammal has a spirit, too. Don’t be thrown off by the word mammal. It’s just human nature, looked at from a different angle—our connection to nonhuman mammals, a well-established fact.

3.. Do nonhuman mammals have souls?

Not in the sense and to the depth that humans have soul. Both share nephesh, however.

4.. Doesn’t the Bible say we are much more valuable than nonhuman mammals (Matt. 12:12)? Are you saying that humans are merely mammals?

No, of course not. We are made in the image of God (note the emphasis in red font in the introduction). Other mammals are not. We are of a higher order than nonhuman mammals. Our spirits-souls can communicate with God and look up to him. One theologian called us homo divinus (divine man) for that reason. But we’re talking about our sin nature in this post, and our sin nature comes from our mammal nature. Indeed, our sin nature resides in our mammal nature.

5.. Are you saying nonhuman mammals sin?

This may be a category mistake in applying guilt and sin to nonhuman animals. But sometimes they seem to exhibit a conscience, when a dog kills a chicken and looks guilty. Koko the gorilla blamed her pet kitten for damaging items in her enclosure during the night. That was a lie. Did she know it was a lie?

6.. How does Adam fit into the picture?

See my post 3. Adam and Evolution: Five Options

7.. So are you saying that we do not inherit sin nature from Adam?

Humanity did, if you translate Adam as his name really means: humankind. After all, the Hebrew noun ’adam is used 558 times in the Hebrew Bible, and it means humanity as a whole: men, women, children together. Only 12 times does it seem to signify the proper name Adam (Gen. 3:17; 3:20-21 [2x]; 4:1, 25; 5:1-5 [4x]; 1 Chron. 1:1 and Hos. 6:7).

So it is best to translate it as “humankind.”

Therefore, yes, we inherit original sin from our human / mammal nature and our broken relationship with God, and this fractured nature is passed on from one generation to the next. Sin is rooted deeply in human origins and human nature. We inherit it from humankind, because we are humankind. We are trapped in our own closed human circuit.

8.. So do humans have free will?

The answer is the same whether we say “mammal nature” or “sin nature.” They have it to a significant degree, and they must deny their sinful nature that is embedded in their mammal nature and exercise their free will to live righteously.

9.. What does this mean for the doctrine of original sin?

As noted, the first option of the doctrine of original sin is sustained, if my thesis is true. Our sin nature flows out our mammal nature because our sin nature is embedded in our mammal nature.

10.. Where does the Fall come in?

The Fall is just one interpretation of Gen. 3, but if you must have this interpretation, then here it is: All human mammals “have sinned and fallen short of the glory of God” (Rom. 3:23). At some time in the primeval past humans fell short, though God’s original intention was for humans to know him intimately. Paul said that primitive humankind knew God, but fell away from or rejected or refused to glorify God (Rom. 1:21). That is a great description of a fall of some kind.

All humans are deficient in their saving knowledge of God, because an unbridgeable gap stands between them and God’s glory, until God bridges the gap through Christ. That’s our “Fall” and our later redemption.

11.. What does your tentative, exploratory thesis say about Paul’s theology in Romans 5:12-21?

If we translate “Adam” as “humankind,” then Paul’s thesis is sustained: through humankind all sin and trespass and death entered the world. Death and sin are built in to humankind’s human / mammal nature. Admittedly, this may make the more restrictive Bible interprets nervous, but I hope they will think about the exploratory thesis in this post. It solves more problems than poses.


Finally, no fear! Just because I use the word mammal does not change the entire structure of theology through and through. The word should not be scary to Christians, because they should not be afraid of scientific facts. This tentative, exploratory thesis of our mammal nature has sustained the Bible description of human sin and Paul’s argument, but with minor adjustments. These small adjustments are not a too steep a price to pay for reasonable believers.

The Bible’s description of human nature is still accurate and still stands. The doctrine of original sin stands.

How does this post help me grow in Jesus?

When humans desire to be in an intimate relationship with God and to be with him in heaven, their mammal / sin nature cannot lead them to the right way. How does this intimacy happen?

They need to go through Christ. “and have put on the new self, which is being renewed in knowledge in the image of its Creator.” (Col. 3:10)

Humans need redemption and salvation to rise above their pure mammal nature, their incomplete and fractured souls. God calls all humans to be redeemed and leave behind their pure mammal nature. How?

Sanctification is a process to walk in holiness and righteousness. God’s Spirit lives in each human who calls on him in Jesus’s name, in order to be restored from brokenness caused by the mammal / sin nature and decisions flowing out of our moral blindness (we don’t realize we have a mammal nature that leads us astray).

God’s big global project for humanity, therefore, is to lift humans out of their mammal / sin nature and restore the image of God in them, through a personal relationship with him through Christ and by the indwelling Holy Spirit.

Finally, church father Irenaeus (flourished 175-195) said, “The glory of God is man fully alive.” When we consider that God’s big global project is to redeem humanity out of its mammal nature and restore the broken image of God, then Irenaeus’s statement is true. God is calling you, whether a believer or unbeliever, to know him better with saving faith and the indwelling of the Holy Spirit. Then you really are the glory of God because you are fully alive in Christ.

Written by James Malcolm


Works Cited at Renewal Theology

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